U.S. patent number 9,608,796 [Application Number 14/265,269] was granted by the patent office on 2017-03-28 for methods and systems for frequency multiplexed communication in dense wireless environments.
This patent grant is currently assigned to QUALCOMM Incorporated. The grantee listed for this patent is QUALCOMM Incorporated. Invention is credited to Gwendolyn Denise Barriac, Simone Merlin, Hemanth Sampath, Rahul Tandra, Bin Tian, Sameer Vermani, Yan Zhou.
United States Patent |
9,608,796 |
Merlin , et al. |
March 28, 2017 |
Methods and systems for frequency multiplexed communication in
dense wireless environments
Abstract
Systems, methods, and devices for high-efficiency wireless
frequency division multiplexing are provided. A method includes
receiving, at a first wireless device, a reference signal from an
associated access point, the reference signal indicative of a time
of joint transmission with at least a second wireless device. The
method further includes transmitting a first communication to the
access point based on the reference signal, the communication
utilizing a first subset of wireless frequencies available for use.
The first communication is concurrent with a second communication,
from the second wireless device, utilizing a second subset of
wireless frequencies, the second subset excluding the first
subset.
Inventors: |
Merlin; Simone (Solana Beach,
CA), Barriac; Gwendolyn Denise (Encinitas, CA), Sampath;
Hemanth (San Diego, CA), Vermani; Sameer (San Diego,
CA), Tian; Bin (San Diego, CA), Zhou; Yan (San Diego,
CA), Tandra; Rahul (San Diego, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
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Assignee: |
QUALCOMM Incorporated (San
Diego, CA)
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Family
ID: |
51841391 |
Appl.
No.: |
14/265,269 |
Filed: |
April 29, 2014 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20140328236 A1 |
Nov 6, 2014 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61819096 |
May 3, 2013 |
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61846579 |
Jul 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
1/18 (20130101); H04W 52/0219 (20130101); H04L
1/1685 (20130101); H04L 5/005 (20130101); H04L
5/0037 (20130101); H04L 5/0094 (20130101); H04B
7/2621 (20130101); H04W 74/02 (20130101); H04J
1/02 (20130101); H04L 5/0005 (20130101); H04W
52/0212 (20130101); H04J 1/14 (20130101); H04B
7/26 (20130101); H04L 5/0073 (20130101); H04L
5/0055 (20130101); H04L 5/0012 (20130101); H04L
5/0069 (20130101); H04W 74/0816 (20130101); H04W
74/002 (20130101); H04L 5/0007 (20130101); H04L
1/1861 (20130101); Y02D 30/70 (20200801); H04L
5/006 (20130101); H04L 2001/0093 (20130101) |
Current International
Class: |
H04L
5/00 (20060101); H04B 7/26 (20060101); H04W
74/02 (20090101); H04L 1/18 (20060101); H04J
1/14 (20060101); H04W 52/02 (20090101); H04J
1/02 (20060101); H04W 74/00 (20090101); H04W
74/08 (20090101); H04L 1/16 (20060101); H04L
1/00 (20060101) |
Field of
Search: |
;370/311 |
References Cited
[Referenced By]
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WO |
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WO |
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Other References
Catt: "UL ACK/NACK Transmission Design in FDD with CA", 3GPP Draft;
R1-100876, 3rd Generation Partnership Project (3GPP), Mobile
Competence Centre ; 650, Route Des Lucioles ; F-06921
Sophia-Antipolis Cedex ; France, vol. RAN WGI, No. San Francisco,
USA; 20100222, Feb. 16, 2010 (Feb. 16, 2010), XP050418480,
[retrieved on Feb. 16, 2010]. cited by applicant .
IEEE 802.11 "Part 11: Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specifications", Mar. 2012, pp. 1-2793. cited
by applicant .
International Search Report and Written
Opinion--PCT/US2014/036190--ISA/EPO--Aug. 13, 2014. cited by
applicant .
Li M., et al., "A dynamic channel assignment method based on
location information of mobile terminals in indoor WLAN positioning
systems", Indoor Positioning and Indoor Navigation (IPIN), 2012
International Conference on, IEEE, Nov. 13, 2012 (Nov. 13, 2012),
pp. 1-9, XP032313189, DOI: 10.1109/IPIN.2012.6418883 ISBN:
978-1-4673-1955-3 the whole document. cited by applicant .
Zhou S., et al., "Distributed Medium Access Control with SDMA
Support for WLANs," IEICE Transactions on Communications,
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Taiwan Search Report--TW103115858--TIPO--Mar. 11, 2016. cited by
applicant.
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Primary Examiner: Pham; Chi H
Assistant Examiner: Lopata; Robert
Attorney, Agent or Firm: Knobbe Martens Olson & Bear
LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application
Nos. 61/819,096, filed May 3, 2013 and 61/846,579, filed Jul. 15,
2013, the entire contents of each of which is incorporated herein
by reference.
Claims
What is claimed is:
1. A method of high-efficiency wireless frequency division
multiplexing, comprising: receiving, at a first wireless device, a
reference signal from an associated access point, the reference
signal indicative of a time of joint transmission with at least a
second wireless device and a deferral time for third party devices,
the reference signal comprising one or more station information
fields, a frame check sequence (FCS), and one or more padding bits
between a final station information field and the FCS, the
reference signal only being sent on a primary channel with an
indication that only idle channels are to be used; and transmitting
a first communication to the associated access point based on the
reference signal, the first communication utilizing a first subset
of wireless frequencies and being concurrent with a second
communication from the second wireless device, the second
communication utilizing a second subset of wireless frequencies,
the second subset of wireless frequencies excluding the first
subset of wireless frequencies.
2. The method of claim 1, further comprising transmitting the
reference signal in response to reception of a ready-to-send (RTX)
frame at the associated access point, the reference signal
comprising a ready-to-send (RTX) frame comprising one or more of: a
frame control field, a duration field, a source address field, a
destination address field, and an information payload comprising
one or more of the following indications: a requested transmission
time, the size of the queues for transmission, a quality-of-service
(QoS) indication for the requested transmission, and a requested
transmission bandwidth.
3. The method of claim 1, the reference signal comprising a
clear-to-send (CTS) comprising a frame including a high throughput
control (HTC) field with an indication reverse decision grant
(RDG)=1.
4. The method of claim 1, the reference signal comprising a frame
including a high throughput control (HTC) field with an indication
reverse decision grant (RDG)=1.
5. The method of claim 1, the reference signal comprising at least
a portion of a power save multi-poll (PSMP) frame, a PSMP-UTT start
offset within a STA info field identifying the start time for
uplink frequency division multiple access (UL FDMA) transmissions,
a PSMP-UTT duration identifies the duration of the UL FDMA
transmission, and a STA ID field comprising an identifier of STAs
allowed to transmit.
6. The method of claim 1, the reference signal further comprising a
frame control field, a duration field, a receive address field, a
transmit address field, and a length field.
7. The method of claim 1, the reference signal including an
indication of the first subset of wireless frequencies.
8. The method of claim 1, further comprising detecting an
interference level on one or more wireless frequencies and
determining the first subset of wireless frequencies based on the
interference level.
9. The method of claim 1, further comprising determining the first
subset of wireless frequencies based on a tone interleaved channel
with frequency hopping.
10. The method of claim 1, the reference signal including an
indication of the first subset of wireless frequencies, and the
method further comprising transmitting the indication of the first
subset of wireless frequencies to one or more devices not
associated with the associated access point.
11. The method of claim 1, the reference signal comprising an
indication of devices that are eligible to transmit at a particular
time.
12. The method of claim 1, the reference signal comprising an
indication of a power level at which at least one device should
transmit.
13. The method of claim 1, the reference signal comprising an
assignment of channels to at least the first wireless device.
14. The method of claim 1, the reference signal comprising an
indication of a transmission time of at least the first wireless
device.
15. The method of claim 1, the reference signal comprising a
clear-to-send frame (CTS).
16. The method of claim 1, the reference signal comprising a
clear-to-send frame (CTS) and an extended payload comprising one or
more payload elements.
17. The method of claim 1, the reference signal comprising a
clear-to-send frame (CTS) comprising a high-throughput control
(HTC) field indicating one or more target devices.
18. The method of claim 1, the reference signal comprising an
aggregated media access control protocol data unit (A-MPDU)
comprising a clear-to-send frame (CTS) and one or more payload
elements.
19. The method of claim 1, further comprising transmitting to the
associated access point a quality-of-service (QoS) field indicating
that the first device is ready to send data.
20. The method of claim 1, further comprising transmitting to the
associated access point a power-save poll (PS-Poll) frame
indicating that the first device is ready to send data.
21. The method of claim 1, wherein the first subset of wireless
frequencies comprises a 20 or 40 or 80 MHz channel according to an
Institute of Electrical and Electronics Engineers (IEEE) 802.11
standard.
22. The method of claim 1, wherein the first and second subset of
wireless frequencies are within an operating bandwidth of the
associated access point.
23. The method of claim 1, wherein the first and second
communications start at the time of joint transmission indicated by
the reference signal, within a margin of transmission time
error.
24. The method of claim 1, wherein the first and second
communications start at different times.
25. The method of claim 1, wherein the first and second
communications end at the time of joint transmission indicated by
the reference signal, within a margin of transmission time
error.
26. The method of claim 1, wherein the first and second
communications end at different times.
27. The method of claim 1, the reference signal being sent by the
associated access point according to a sense multiple access (CSMA)
mechanism.
28. The method of claim 1, the reference signal being sent by the
associated access point at a time previously scheduled with at
least the first device via management signaling.
29. The method of claim 1, the reference signal comprising
management signaling indicating one or more future times of joint
transmission.
30. The method of claim 1, wherein the reference signal is sent at
least on a primary channel.
31. The method of claim 1, wherein the reference signal is sent on
a primary channel and on all or a portion of secondary channels
that are idle for a sensing time before the transmission.
32. The method of claim 1, wherein the reference signal is sent on
channels compatible with the first and second devices.
33. The method of claim 1, wherein at least the first device
indicates to the associated access point a channel use
capability.
34. The method of claim 1, wherein the reference signal is sent on
idle channels only.
35. A first wireless device configured to perform high-efficiency
wireless frequency division multiplexing, comprising: a receiver
configured to receive a reference signal from an associated access
point, the reference signal indicative of a time of joint
transmission with at least a second wireless device and a deferral
time for third party devices, the reference signal comprising one
or more station information fields, a frame check sequence (FCS),
and one or more padding bits between a final station information
field and the FCS, the reference signal only being sent on a
primary channel with an indication that only idle channels are to
be used; and a transmitter configured to transmit a first
communication to the associated access point based on the reference
signal, the first communication utilizing a first subset of
wireless frequencies and being concurrent with a second
communication from the second wireless device, the second
communication utilizing a second subset of wireless frequencies,
the second subset of wireless frequencies excluding the first
subset of wireless frequencies.
36. The device of claim 35, the transmitter being further
configured to transmit the reference signal in response to
reception of a ready-to-send (RTX) frame at the associated access
point, the reference signal comprising a ready-to-send (RTX) frame
comprising one or more of: a frame control field, a duration field,
a source address field, a destination address field, and an
information payload comprising one or more of the following
indications: a requested transmission time, the size of the queues
for transmission, a quality-of-service (QoS) indication for the
requested transmission, and a requested transmission bandwidth.
37. The device of claim 35, the reference signal comprising a
clear-to-send (CTS) frame comprising a frame including a high
throughput control (HTC) field with an indication reverse decision
grant (RDG)=1.
38. The device of claim 35, the reference signal comprising a frame
including a high throughput control (HTC) field with an indication
reverse decision grant (RDG)=1.
39. The device of claim 35, the reference signal comprising at
least a portion of a power save multi-poll (PSMP) frame, a PSMP-UTT
start offset within a STA info field identifying the start time for
uplink frequency division multiple access (UL FDMA) transmissions,
a PSMP-UTT duration identifies the duration of the UL FDMA
transmission, and a STA ID field comprising an identifier of STAs
allowed to transmit.
40. The device of claim 35, the reference signal further comprising
a frame control field, a duration field, a receive address field, a
transmit address field, and a length field.
41. The device of claim 35, the reference signal including an
indication of the first subset of wireless frequencies.
42. The device of claim 35, further comprising a processor
configured to detect an interference level on one or more wireless
frequencies and determining the first subset of wireless
frequencies based on the interference level.
43. The device of claim 35, further comprising a processor
configured to determine the first subset of wireless frequencies
based on a tone interleaved channel with frequency hopping.
44. The device of claim 35, the reference signal including an
indication of the first subset of wireless frequencies, and the
transmitter being further configured to transmit the indication of
the first subset of wireless frequencies to one or more devices not
associated with the associated access point.
45. The device of claim 35, the reference signal comprising an
indication of devices that are eligible to transmit at a particular
time.
46. The device of claim 35, the reference signal comprising an
indication of a power level at which at least one device should
transmit.
47. The device of claim 35, the reference signal comprising an
assignment of channels to at least the first wireless device.
48. The device of claim 35, the reference signal comprising an
indication of a transmission time of at least the first wireless
device.
49. The device of claim 35, the reference signal comprising a
clear-to-send frame (CTS).
50. The device of claim 35, the reference signal comprising a
clear-to-send frame (CTS) and an extended payload comprising one or
more payload elements.
51. The device of claim 35, the reference signal comprising a
clear-to-send frame (CTS) comprising a high-throughput control
(HTC) field indicating one or more target devices.
52. The device of claim 35, the reference signal comprising an
aggregated media access control protocol data unit (A-MPDU)
comprising a clear-to-send frame (CTS) and one or more payload
elements.
53. The device of claim 35, the transmitter being further
configured to transmit to the associated access point a
quality-of-service (QoS) field indicating that the first device is
ready to send data.
54. The device of claim 35, the transmitter being further
configured to transmit to the associated access point a power-save
poll (PS-Poll) frame indicating that the first device is ready to
send data.
55. The device of claim 35, wherein the first subset of wireless
frequencies comprises a 20 or 40 or 80 MHz channel according to an
Institute of Electrical and Electronics Engineers (IEEE) 802.11
standard.
56. The device of claim 35, wherein the first and second subset of
wireless frequencies are within an operating bandwidth of the
associated access point.
57. The device of claim 35, wherein the first and second
communications start at the time of joint transmission indicated by
the reference signal, within a margin of transmission time
error.
58. The device of claim 35, wherein the first and second
communications start at different times.
59. The device of claim 35, wherein the first and second
communications end at the time of joint transmission indicated by
the reference signal, within a margin of transmission time
error.
60. The device of claim 35, wherein the first and second
communications end at different times.
61. The device of claim 35, the reference signal being sent by the
associated access point according to a sense multiple access (CSMA)
mechanism.
62. The device of claim 35, the reference signal being sent by the
associated access point at a time previously scheduled with at
least the first device via management signaling.
63. The device of claim 35, the reference signal comprising
management signaling indicating one or more future times of joint
transmission.
64. The device of claim 35, wherein the reference signal is sent at
least on a primary channel.
65. The device of claim 35, wherein the reference signal is sent on
a primary channel and on all or a portion of secondary channels
that are idle for a sensing time before the transmission.
66. The device of claim 35, wherein the reference signal is sent on
channels compatible with the first and second devices.
67. The device of claim 35, wherein at least the first device
indicates to the associated access point a channel use
capability.
68. The device of claim 35, wherein the reference signal is sent on
idle channels only.
69. An apparatus for high-efficiency wireless frequency division
multiplexing, comprising: means for receiving, at a first wireless
device, a reference signal from an associated access point, the
reference signal indicative of a time of joint transmission with at
least a second wireless device and a deferral time for third party
devices, the reference signal comprising one or more station
information fields, a frame check sequence (FCS), and one or more
padding bits between a final station information field and the FCS,
the reference signal only being sent on a primary channel with an
indication that only idle channels are to be used; and means for
transmitting a first communication to the associated access point
based on the reference signal, the first communication utilizing a
first subset of wireless frequencies and being concurrent with a
second communication from the second wireless device, the second
communication utilizing a second subset of wireless frequencies,
the second subset of wireless frequencies excluding the first
subset of wireless frequencies.
70. A non-transitory computer-readable medium comprising code that,
when executed, causes an apparatus to: receive, at a first wireless
device, a reference signal from an associated access point, the
reference signal indicative of a time of joint transmission with at
least a second wireless device and a deferral time for third party
devices, the reference signal comprising one or more station
information fields, a frame check sequence (FCS), and one or more
padding bits between a final station information field and the FCS,
the reference signal only being sent on a primary channel with an
indication that only idle channels are to be used; and transmit a
first communication to the associated access point based on the
reference signal, the first communication utilizing a first subset
of wireless frequencies and being concurrent with a second
communication from the second wireless device, the second
communication utilizing a second subset of wireless frequencies,
the second subset of wireless frequencies excluding the first
subset of wireless frequencies.
Description
FIELD
The present application relates generally to wireless
communications, and more specifically to systems, methods, and
devices for frequency multiplexed wireless communication in dense
wireless environments.
BACKGROUND
In many telecommunication systems, communications networks are used
to exchange messages among several interacting spatially-separated
devices. Networks can be classified according to geographic scope,
which could be, for example, a metropolitan area, a local area, or
a personal area. Such networks would be designated respectively as
a wide area network (WAN), metropolitan area network (MAN), local
area network (LAN), wireless local area network (WLAN), or personal
area network (PAN). Networks also differ according to the
switching/routing technique used to interconnect the various
network nodes and devices (for example, circuit switching vs.
packet switching), the type of physical media employed for
transmission (for example, wired vs. wireless), and the set of
communication protocols used (for example, Internet protocol suite,
SONET (Synchronous Optical Networking), Ethernet, etc.).
Wireless networks are often preferred when the network elements are
mobile and thus have dynamic connectivity needs, or if the network
architecture is formed in an ad hoc, rather than fixed, topology.
Wireless networks employ intangible physical media in an unguided
propagation mode using electromagnetic waves in the radio,
microwave, infra-red, optical, etc. frequency bands. Wireless
networks advantageously facilitate user mobility and rapid field
deployment when compared to fixed wired networks.
However, multiple wireless networks may exist in the same building,
in nearby buildings, and/or in the same outdoor area. The
prevalence of multiple wireless networks may cause interference,
reduced throughput (for example, because each wireless network is
operating in the same area and/or spectrum), and/or prevent certain
devices from communicating. Thus, improved systems, methods, and
devices for communicating when wireless networks are densely
populated are desired.
SUMMARY
The systems, methods, and devices of the invention each have
several aspects, no single one of which is solely responsible for
its desirable attributes. Without limiting the scope of this
invention as expressed by the claims which follow, some features
will now be discussed briefly. After considering this discussion,
and particularly after reading the section entitled "Detailed
Description" one will understand how the features of this invention
provide advantages that include improved communications between
access points and stations in a wireless network.
One aspect of this disclosure provides a method of high-efficiency
wireless frequency division multiplexing. The method includes
determining, at an access point, a performance characteristic for
each wireless device in a set of wireless devices associated with
the access point. The method further includes categorizing each
wireless device in the set into at least a first and second subset
of wireless devices based on the performance characteristic. The
method further includes receiving communications from the first
subset of wireless devices on a first set of wireless frequencies.
The method further includes receiving communications from the
second subset of wireless devices on a second set of wireless
frequencies, the second set of wireless frequencies being a subset
of the first. The first set of wireless devices have a higher
performance characteristic than the second set of wireless
devices.
Another aspect provides an access point configured to perform
high-efficiency wireless frequency division multiplexing. The
access point includes a processor configured to determine a
performance characteristic for each wireless device in a set of
wireless devices associated with the access point. The processor is
further configured to categorize each wireless device in the set
into at least a first and second subset of wireless devices based
on the performance characteristic. The access point further
includes a receiver configured to receive communications from the
first subset of wireless devices on a first set of wireless
frequencies. The receiver is further configured to receive
communications from the second subset of wireless devices on a
second set of wireless frequencies, the second set of wireless
frequencies being a subset of the first. The first set of wireless
devices have a higher performance characteristic than the second
set of wireless devices.
Another aspect provides an apparatus for high-efficiency wireless
frequency division multiplexing. The apparatus includes means for
determining, at an access point, a performance characteristic for
each wireless device in a set of wireless devices associated with
the access point. The apparatus further includes means for
categorizing each wireless device in the set into at least a first
and second subset of wireless devices based on the performance
characteristic. The apparatus further includes means for receiving
communications from the first subset of wireless devices on a first
set of wireless frequencies. The apparatus further includes means
for receiving communications from the second subset of wireless
devices on a second set of wireless frequencies, the second set of
wireless frequencies being a subset of the first. The first set of
wireless devices have a higher performance characteristic than the
second set of wireless devices.
Another aspect provides a non-transitory computer-readable medium
including code that, when executed, causes an apparatus to
determine, at an access point, a performance characteristic for
each wireless device in a set of wireless devices associated with
the access point. The medium further includes code that, when
executed, causes the apparatus to categorize each wireless device
in the set into at least a first and second subset of wireless
devices based on the performance characteristic. The medium further
includes code that, when executed, causes the apparatus to receive
communications from the first subset of wireless devices on a first
set of wireless frequencies. The medium further includes code that,
when executed, causes the apparatus to receive communications from
the second subset of wireless devices on a second set of wireless
frequencies, the second set of wireless frequencies being a subset
of the first. The first set of wireless devices have a higher
performance characteristic than the second set of wireless
devices.
Another aspect provides a method of high-efficiency wireless
frequency division multiplexing. The method includes receiving, at
a first wireless device, a reference signal from an associated
access point, the reference signal indicative of a time of joint
transmission with at least a second wireless device. The method
further includes transmitting a first communication to the access
point based on the reference signal, the communication utilizing a
first subset of wireless frequencies available for use. The first
communication is concurrent with a second communication, from the
second wireless device, utilizing a second subset of wireless
frequencies, the second subset excluding the first subset.
Another aspect provides a first wireless device configured to
perform high-efficiency wireless frequency division multiplexing.
The device includes a receiver configured to receive a reference
signal from an associated access point, the reference signal
indicative of a time of joint transmission with at least a second
wireless device. The device further includes a transmitter
configured to transmit a first communication to the access point
based on the reference signal, the communication utilizing a first
subset of wireless frequencies available for use. The first
communication is concurrent with a second communication, from the
second wireless device, utilizing a second subset of wireless
frequencies, the second subset excluding the first subset.
Another aspect provides an apparatus for high-efficiency wireless
frequency division multiplexing. The apparatus includes means for
receiving, at a first wireless device, a reference signal from an
associated access point, the reference signal indicative of a time
of joint transmission with at least a second wireless device. The
apparatus further includes means for transmitting a first
communication to the access point based on the reference signal,
the communication utilizing a first subset of wireless frequencies
available for use. The first communication is concurrent with a
second communication, from the second wireless device, utilizing a
second subset of wireless frequencies, the second subset excluding
the first subset.
Another aspect provides non-transitory computer-readable medium
including code that, when executed, causes an apparatus to receive,
at a first wireless device, a reference signal from an associated
access point, the reference signal indicative of a time of joint
transmission with at least a second wireless device. The medium
further includes code that, when executed, causes the apparatus to
transmit a first communication to the access point based on the
reference signal, the communication utilizing a first subset of
wireless frequencies available for use. The first communication is
concurrent with a second communication, from the second wireless
device, utilizing a second subset of wireless frequencies, the
second subset excluding the first subset.
Another aspect provides a method of high-efficiency wireless
frequency division multiplexing. The method includes exchanging, at
an access point, at least one protection frame with at least one of
a first and second wireless device. The method further includes
receiving a first communication on a first set of wireless
frequencies from at least the first wireless device device. The
method further includes receiving a second communication, at least
partially concurrent with the first communication, on a second set
of wireless frequencies from the second wireless device. The method
further includes transmitting at least one acknowledgment of the
first and second communication. The first set and the second set
are mutually exclusive subsets of a set of wireless frequencies
available for use by both the first and second wireless device.
Another aspect provides an access point configured to perform
high-efficiency wireless frequency division multiplexing. The
access point includes a processor configured to exchange at least
one protection frame with at least one of a first and second
wireless device. The access point further includes a receiving
configured to receive a first communication on a first set of
wireless frequencies from at least the first wireless device
device. The receiver is further configured to receive a second
communication, at least partially concurrent with the first
communication, on a second set of wireless frequencies from the
second wireless device. The access point further includes a
transmitter configured to transmit at least one acknowledgment of
the first and second communication. The first set and the second
set are mutually exclusive subsets of a set of wireless frequencies
available for use by both the first and second wireless device.
Another aspect provides an apparatus for high-efficiency wireless
frequency division multiplexing. The apparatus includes means for
exchanging, at an access point, at least one protection frame with
at least one of a first and second wireless device. The apparatus
further includes means for receiving a first communication on a
first set of wireless frequencies from at least the first wireless
device device. The apparatus further includes means for receiving a
second communication, at least partially concurrent with the first
communication, on a second set of wireless frequencies from the
second wireless device. The apparatus further includes means for
transmitting at least one acknowledgment of the first and second
communication. The first set and the second set are mutually
exclusive subsets of a set of wireless frequencies available for
use by both the first and second wireless device.
Another aspect provides a non-transitory computer-readable medium
including code that, when executed, causes an apparatus to
exchange, at an access point, at least one protection frame with at
least one of a first and second wireless device. The medium further
includes code that, when executed, causes the apparatus to receive
a first communication on a first set of wireless frequencies from
at least the first wireless device device. The medium further
includes code that, when executed, causes the apparatus to receive
a second communication, at least partially concurrent with the
first communication, on a second set of wireless frequencies from
the second wireless device. The medium further includes code that,
when executed, causes the apparatus to transmit at least one
acknowledgment of the first and second communication. The first set
and the second set are mutually exclusive subsets of a set of
wireless frequencies available for use by both the first and second
wireless device.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an exemplary wireless communication system in which
aspects of the present disclosure can be employed.
FIG. 2A shows a wireless communication system in which multiple
wireless communication networks are present.
FIG. 2B shows another wireless communication system in which
multiple wireless communication networks are present.
FIG. 3 shows frequency multiplexing techniques that can be employed
within the wireless communication systems of FIGS. 1 and 2B.
FIG. 4 shows a functional block diagram of an exemplary wireless
device that can be employed within the wireless communication
systems of FIGS. 1, 2B, and 3.
FIG. 5A shows the wireless communication system in which aspects of
the present disclosure can be employed.
FIGS. 5B-5C show a timing diagram in which aspects of the present
disclosure can be employed.
FIGS. 6A-6C show another timing diagram in which aspects of the
present disclosure can be employed.
FIGS. 6D-6F show another timing diagram in which aspects of the
present disclosure can be employed.
FIG. 7A shows an example reference signal that can be employed
within the wireless communication systems of FIGS. 1, 2B, and
3.
FIG. 7B shows exemplary reference signal formats and fields that
can be employed within the wireless communication systems of FIGS.
1, 2B, and 3.
FIG. 7C shows an example reference signal that can be employed
within the wireless communication systems of FIGS. 1, 2B, and
3.
FIG. 8 shows another timing diagram in which aspects of the present
disclosure can be employed.
FIGS. 9A-9D show additional timing diagrams in which aspects of the
present disclosure can be employed.
FIG. 10 shows a flowchart for an exemplary method of wireless
communication that can be employed within the wireless
communication system 500 of FIG. 5.
FIG. 11 shows a flowchart for another exemplary method of wireless
communication that can be employed within the wireless
communication system 500 of FIG. 5.
FIG. 12 shows a flowchart for an exemplary method of wireless
communication that can be employed within the wireless
communication system 500 of FIG. 5.
DETAILED DESCRIPTION
Various aspects of the novel systems, apparatuses, and methods are
described more fully hereinafter with reference to the accompanying
drawings. This disclosure may, however, be embodied in many
different forms and should not be construed as limited to any
specific structure or function presented throughout this
disclosure. Rather, these aspects are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the disclosure to those skilled in the art. Based on the
teachings herein one skilled in the art should appreciate that the
scope of the disclosure is intended to cover any aspect of the
novel systems, apparatuses, and methods disclosed herein, whether
implemented independently of, or combined with, any other aspect of
the invention. For example, an apparatus can be implemented or a
method can be practiced using any number of the aspects set forth
herein. In addition, the scope of the invention is intended to
cover such an apparatus or method which is practiced using other
structure, functionality, or structure and functionality in
addition to or other than the various aspects of the invention set
forth herein. It should be understood that any aspect disclosed
herein can be embodied by one or more elements of a claim.
Although particular aspects are described herein, many variations
and permutations of these aspects fall within the scope of the
disclosure. Although some benefits and advantages of the preferred
aspects are mentioned, the scope of the disclosure is not intended
to be limited to particular benefits, uses, or objectives. Rather,
aspects of the disclosure are intended to be broadly applicable to
different wireless technologies, system configurations, networks,
and transmission protocols, some of which are illustrated by way of
example in the figures and in the following description of the
preferred aspects. The detailed description and drawings are merely
illustrative of the disclosure rather than limiting, the scope of
the disclosure being defined by the appended claims and equivalents
thereof.
Popular wireless network technologies may include various types of
wireless local area networks (WLANs). A WLAN can be used to
interconnect nearby devices together, employing widely used
networking protocols. The various aspects described herein may
apply to any communication standard, such as a wireless
protocol.
In some aspects, wireless signals can be transmitted according to a
high-efficiency 802.11 protocol using orthogonal frequency-division
multiplexing (OFDM), direct-sequence spread spectrum (DSSS)
communications, a combination of OFDM and DSSS communications, or
other schemes. Implementations of the high-efficiency 802.11
protocol can be used for Internet access, sensors, metering, smart
grid networks, or other wireless applications. Advantageously,
aspects of certain devices implementing the high-efficiency 802.11
protocol using the techniques disclosed herein may include allowing
for increased peer-to-peer services (for example, Miracast, WiFi
Direct Services, Social WiFi, etc.) in the same area, supporting
increased per-user minimum throughput requirements, supporting more
users, providing improved outdoor coverage and robustness, and/or
consuming less power than devices implementing other wireless
protocols.
In some implementations, a WLAN includes various devices which are
the components that access the wireless network. For example, there
can be two types of devices: access points ("APs") and clients
(also referred to as stations, or "STAs"). In general, an AP may
serve as a hub or base station for the WLAN and an STA serves as a
user of the WLAN. For example, an STA can be a laptop computer, a
personal digital assistant (PDA), a mobile phone, etc. In an
example, an STA connects to an AP via a WiFi (for example, IEEE
802.11 protocol) compliant wireless link to obtain general
connectivity to the Internet or to other wide area networks. In
some implementations an STA may also be used as an AP.
An access point ("AP") may also comprise, be implemented as, or
known as a NodeB, Radio Network Controller ("RNC"), eNodeB, Base
Station Controller ("BSC"), Base Transceiver Station ("BTS"), Base
Station ("BS"), Transceiver Function ("TF"), Radio Router, Radio
Transceiver, or some other terminology.
A station "STA" may also comprise, be implemented as, or known as
an access terminal ("AT"), a subscriber station, a subscriber unit,
a mobile station, a remote station, a remote terminal, a user
terminal, a user agent, a user device, user equipment, or some
other terminology. In some implementations an access terminal may
comprise a cellular telephone, a cordless telephone, a Session
Initiation Protocol ("SIP") phone, a wireless local loop ("WLL")
station, a personal digital assistant ("PDA"), a handheld device
having wireless connection capability, or some other suitable
processing device connected to a wireless modem. Accordingly, one
or more aspects taught herein can be incorporated into a phone (for
example, a cellular phone or smartphone), a computer (for example,
a laptop), a portable communication device, a headset, a portable
computing device (for example, a personal data assistant), an
entertainment device (for example, a music or video device, or a
satellite radio), a gaming device or system, a global positioning
system device, or any other suitable device that is configured to
communicate via a wireless medium.
As discussed above, certain of the devices described herein may
implement a high-efficiency 802.11 standard, for example. Such
devices, whether used as an STA or AP or other device, can be used
for smart metering or in a smart grid network. Such devices may
provide sensor applications or be used in home automation. The
devices may instead or in addition be used in a healthcare context,
for example for personal healthcare. They may also be used for
surveillance, to enable extended-range Internet connectivity (for
example, for use with hotspots), or to implement machine-to-machine
communications.
FIG. 1 shows an exemplary wireless communication system 100 in
which aspects of the present disclosure can be employed. The
wireless communication system 100 may operate pursuant to a
wireless standard, for example a high-efficiency 802.11 standard.
The wireless communication system 100 may include an AP 104, which
communicates with STAs 106.
A variety of processes and methods can be used for transmissions in
the wireless communication system 100 between the AP 104 and the
STAs 106. For example, signals can be sent and received between the
AP 104 and the STAs 106 in accordance with OFDM/OFDMA techniques.
If this is the case, the wireless communication system 100 can be
referred to as an OFDM/OFDMA system. Alternatively, signals can be
sent and received between the AP 104 and the STAs 106 in accordance
with code division multiple access (CDMA) techniques. If this is
the case, the wireless communication system 100 can be referred to
as a CDMA system.
A communication link that facilitates transmission from the AP 104
to one or more of the STAs 106 can be referred to as a downlink
(DL) 108, and a communication link that facilitates transmission
from one or more of the STAs 106 to the AP 104 can be referred to
as an uplink (UL) 110. Alternatively, a downlink 108 can be
referred to as a forward link or a forward channel, and an uplink
110 can be referred to as a reverse link or a reverse channel.
The AP 104 may act as a base station and provide wireless
communication coverage in a basic service area (BSA) 102. The AP
104 along with the STAs 106 associated with the AP 104 and that use
the AP 104 for communication can be referred to as a basic service
set (BSS). It should be noted that the wireless communication
system 100 may not have a central AP 104, but rather may function
as a peer-to-peer network between the STAs 106. Accordingly, the
functions of the AP 104 described herein may alternatively be
performed by one or more of the STAs 106.
In some aspects, a STA 106 can be required to associate with the AP
104 in order to send communications to and/or receive
communications from the AP 104. In one aspect, information for
associating is included in a broadcast by the AP 104. To receive
such a broadcast, the STA 106 may, for example, perform a broad
coverage search over a coverage region. A search may also be
performed by the STA 106 by sweeping a coverage region in a
lighthouse fashion, for example. After receiving the information
for associating, the STA 106 may transmit a reference signal, such
as an association probe or request, to the AP 104. In some aspects,
the AP 104 may use backhaul services, for example, to communicate
with a larger network, such as the Internet or a public switched
telephone network (PSTN).
In an embodiment, the AP 104 includes an AP high-efficiency
wireless component (HEWC) 154. The AP HEWC 154 may perform some or
all of the operations described herein to enable communications
between the AP 104 and the STAs 106 using the high-efficiency
802.11 protocol. The functionality of some implementations of the
AP HEWC 154 is described in greater detail below with respect to
FIGS. 2B, 3, 4, and 8.
Alternatively or in addition, the STAs 106 may include a STA HEWC
156. The STA HEWC 156 may perform some or all of the operations
described herein to enable communications between the STAs 106 and
the AP 104 using the high-frequency 802.11 protocol. The
functionality of some implementations of the STA HEWC 156 is
described in greater detail below with respect to FIGS. 2B, 3, 4,
8B, and 10B.
In some circumstances, a BSA can be located near other BSAs. For
example, FIG. 2A shows a wireless communication system 200 in which
multiple wireless communication networks are present. As
illustrated in FIG. 2A, BSAs 202A, 202B, and 202C can be physically
located near each other. Despite the close proximity of the BSAs
202A-202C, the APs 204A-204C and/or STAs 206A-206H may each
communicate using the same spectrum. Thus, if a device in the BSA
202C (for example, the AP 204C) is transmitting data, devices
outside the BSA 202C (for example, APs 204A-204B or STAs 206A-206F)
may sense the communication on the medium.
Generally, wireless networks that use a regular 802.11 protocol
(for example, 802.11a, 802.11b, 802.11g, 802.11n, etc.) operate
under a carrier sense multiple access (CSMA) mechanism for medium
access. According to CSMA, devices sense the medium and only
transmit when the medium is sensed to be idle. Thus, if the APs
204A-204C and/or STAs 206A-206H are operating according to the CSMA
mechanism and a device in the BSA 202C (for example, the AP 204C)
is transmitting data, then the APs 204A-204B and/or STAs 206A-206F
outside of the BSA 202C may not transmit over the medium even
though they are part of a different BSA.
FIG. 2A illustrates such a situation. As illustrated in FIG. 2A, AP
204C is transmitting over the medium. The transmission is sensed by
STA 206G, which is in the same BSA 202C as the AP 204C, and by STA
206A, which is in a different BSA than the AP 204C. While the
transmission can be addressed to the STA 206G and/or only STAs in
the BSA 202C, STA 206A nonetheless may not be able to transmit or
receive communications (for example, to or from the AP 204A) until
the AP 204C (and any other device) is no longer transmitting on the
medium. Although not shown, the same may apply to STAs 206D-206F in
the BSA 202B and/or STAs 206B-206C in the BSA 202A as well (for
example, if the transmission by the AP 204C is stronger such that
the other STAs can sense the transmission on the medium).
The use of the CSMA mechanism then creates inefficiencies because
some APs or STAs outside of a BSA can be able to transmit data
without interfering with a transmission made by an AP or STA in the
BSA. As the number of active wireless devices continues to grow,
the inefficiencies can begin to significantly affect network
latency and throughput. For example, significant network latency
issues may appear in apartment buildings, in which each apartment
unit may include an access point and associated stations. In fact,
each apartment unit may include multiple access points, as a
resident may own a wireless router, a video game console with
wireless media center capabilities, a television with wireless
media center capabilities, a cell phone that can act like a
personal hot-spot, and/or the like. Correcting the inefficiencies
of the CSMA mechanism may then be vital to avoid latency and
throughput issues and overall user dissatisfaction.
Such latency and throughput issues may not be confined to
residential areas. For example, multiple access points can be
located in airports, subway stations, and/or other
densely-populated public spaces. Currently, WiFi access can be
offered in these public spaces, but for a fee. If the
inefficiencies created by the CSMA mechanism are not corrected,
then operators of the wireless networks may lose customers as the
fees and lower quality of service begin to outweigh any
benefits.
Accordingly, the high-efficiency 802.11 protocol described herein
may allow for devices to operate under a modified mechanism that
minimizes these inefficiencies and increases network throughput.
Such a mechanism is described below with respect to FIGS. 2B, 3,
and 4. Additional aspects of the high-efficiency 802.11 protocol
are described below with respect to FIGS. 5-13.
FIG. 2B shows a wireless communication system 250 in which multiple
wireless communication networks are present. Unlike the wireless
communication system 200 of FIG. 2A, the wireless communication
system 250 may operate pursuant to the high-efficiency 802.11
standard discussed herein. The wireless communication system 250
may include an AP 254A, an AP 254B, and an AP 254C. The AP 254A may
communicate with STAs 256A-256C, the AP 254B may communicate with
STAs 256D-256F, and the AP 254C may communicate with STAs
256G-256H.
A variety of processes and methods can be used for transmissions in
the wireless communication system 250 between the APs 254A-254C and
the STAs 256A-256H. For example, signals can be sent and received
between the APs 254A-254C and the STAs 256A-256H in accordance with
OFDM/OFDMA techniques or CDMA techniques.
The AP 254A may act as a base station and provide wireless
communication coverage in a BSA 252A. The AP 254B may act as a base
station and provide wireless communication coverage in a BSA 252B.
The AP 254C may act as a base station and provide wireless
communication coverage in a BSA 252C. It should be noted that each
BSA 252A, 252B, and/or 252C may not have a central AP 254A, 254B,
or 254C, but rather may allow for peer-to-peer communications
between one or more of the STAs 256A-256H. Accordingly, the
functions of the AP 254A-254C described herein may alternatively be
performed by one or more of the STAs 256A-256H.
In an embodiment, the APs 254A-254C and/or STAs 256A-256H include a
high-efficiency wireless component. As described herein, the
high-efficiency wireless component may enable communications
between the APs and STAs using the high-efficiency 802.11 protocol.
In particular, the high-efficiency wireless component may enable
the APs 254A-254C and/or STAs 256A-256H to use a modified mechanism
that minimizes the inefficiencies of the CSMA mechanism (for
example, enables concurrent communications over the medium in
situations in which interference would not occur). The
high-efficiency wireless component is described in greater detail
below with respect to FIG. 4.
As illustrated in FIG. 2B, the BSAs 252A-252C are physically
located near each other. When, for example, AP 254A and STA 256B
are communicating with each other, the communication can be sensed
by other devices in BSAs 252B-252C. However, the communication may
only interfere with certain devices, such as STA 256F and/or STA
256G. Under CSMA, AP 254B would not be allowed to communicate with
STA 256E even though such communication would not interfere with
the communication between AP 254A and STA 256B. Thus, the
high-efficiency 802.11 protocol operates under a modified mechanism
that differentiates between devices that can communicate
concurrently and devices that cannot communicate concurrently. In
various embodiments used herein, "concurrently" can mean at least
partially overlapping in time. Such classification of devices can
be performed by the high-efficiency wireless component in the APs
254A-254C and/or the STAs 256A-256H.
In an embodiment, the determination of whether a device can
communicate concurrently with other devices is based on a
"location" of the device. For example, a STA that is located near
an "edge" of the BSA can be in a state or condition such that the
STA cannot communicate concurrently with other devices. As
illustrated in FIG. 2B, STAs 206A, 206F, and 206G can be devices
that are in a state or condition in which they cannot communicate
concurrently with other devices. Likewise, a STA that is located
near the center of the BSA can be in a station or condition such
that the STA can communicate concurrently with other devices. As
illustrated in FIG. 2B, STAs 206B, 206C, 206D, 206E, and 206H can
be devices that are in a state or condition in which they can
communicate concurrently with other devices. Note that the
classification of devices is not permanent. Devices may transition
between being in a state or condition such that they can
communicate concurrently and being in a state or condition such
that they cannot communicate concurrently (for example, devices may
change states or conditions when in motion, when associating with a
new AP, when disassociating, etc.).
As used herein, a device can be classified as an "edge" device
based on a physical location, a radio "location" (for example, a
radio frequency characteristic), or a combination thereof. For
example, in the illustrated embodiment, the STA 256B can be
physically close to the AP 254A. Accordingly, the STA 256B can be
classified as an inner-cell device (i.e., not an "edge" device)
based on its physical proximity to the AP 254A. Particularly, the
STA 256B can be likely to successfully communicate with the AP
254A, even while the STA 256G is concurrently transmitting.
On the other hand, the STA 256C can be physically close to the AP
254A, but its antenna might be oriented poorly for communication
with the AP 254A. For example, it's the STA 256C could have a
directional antenna pointed at the STA 256G. Accordingly, although
the STA 256C might be physically close to the AP 254A, it can be
classified as an edge device due to poor RF characteristics with
respect to the AP 254A. In other words, the STA 256C might be
unlikely to successfully communicate with the AP 254A while the STA
256G is concurrently transmitting.
In another example, the STA 256A might be physically close to the
AP 254A, but it might also be physically close to the STA 256G. Due
to the proximity between the STA 256A and the STA 256G, the STA
256A might be unlikely to successfully communicate with the AP 254A
while the STA 256G is concurrently transmitting. In this
embodiment, the STA 256A might also be characterized as an edge
device.
In various embodiments, RF characteristics that affect the
characterization of a STA as an inner-cell device or a cell-edge
device can include one or more of: a
signal-to-interference-plus-noise ratio (SINR), an RF geometry, a
received signal strength indicator (RSSI), a modulation and coding
scheme (MCS) value, an interference level, a signal level, etc. In
various embodiments, one or more physical and RF characteristics
can be compared to one or more threshold levels. The comparisons
can be weighted and/or combined. In various embodiments, devices
can be determined to be in a condition such that they can or cannot
communicate concurrently based on the solitary, weighted, and/or
combined physical and RF characteristics and associated
thresholds.
Devices can be configured to behave differently based on whether
they are ones that are or are not in a state or condition to
communicate concurrently with other devices. For example, devices
that are in a state or condition such that they can communicate
concurrently (which can be referred to herein as "inner cell"
devices) may communicate within the same spectrum. However, devices
that are in a state or condition such that they cannot communicate
concurrently (which can be referred to herein as "cell-edge"
devices) may employ certain techniques, such as spatial
multiplexing or frequency domain multiplexing, in order to
communicate over the medium. The controlling of the behavior of the
devices can be performed by the high-efficiency wireless component
in the APs 254A-254C and/or the STAs 256A-256H.
In an embodiment, cell-edge devices use spatial multiplexing
techniques to communicate over the medium. For example, power
and/or other information can be embedded within the preamble of a
packet transmitted by another device. A device in a state or
condition such that the device cannot communicate concurrently may
analyze the preamble when the packet is sensed on the medium and
decide whether or not to transmit based on a set of rules.
In another embodiment, cell-edge devices use frequency domain
multiplexing techniques to communicate over the medium. For
example, in one embodiment, a first subset of cell-edge devices can
communicate using a first subset of available bandwidth. A second
subset of cell-edge devices can communicate using a second subset
of available bandwidth. Meanwhile, inner cell devices can
communicate using an entirety of available bandwidth, or a third
subset of available bandwidth. In various embodiments, the third
subset can be larger than the first and/or second subsets. In some
embodiments, the third subset can intersect with the first and/or
second subsets. In some embodiments, the third subset can include
all available bandwidth (for example, all bandwidth licensed for
use according to a specific technology such as 802.11). Although
channels, sub-channels, available bandwidth, and subsets thereof,
are generally depicted herein as contiguous, a person having
ordinary skill in the art will appreciate that the terms used
herein can also encompass contiguous frequencies, interleaved
frequencies, sets of adjacent or non-adjacent tones with or without
frequency hopping, etc.
For example, with continuing reference to FIG. 2B, STAs 256A, 256C,
and 256G can be cell-edge devices, while STAs 256B and 256H can be
inner-cell devices. Accordingly, in an embodiment, the STAs 256A
and 256C may form a first subset of cell-edge devices configured to
communicate with the AP 254A on a first sub-channel (or set of
sub-channels). The first subset of cell-edge devices can be
associated with a first BSA 252A. The STA 256G may form a second
subset of cell-edge devices configured to communicate with the AP
254C on a second sub-channel (or set of sub-channels), which can be
orthogonal to the first sub-channel. The second subset of cell-edge
devices can be associated with a second BSA 252C. Thus, in an
embodiment, the STA 256A can communicate at the same time (but on a
different sub-channel) as the STA 256G.
Meanwhile, the STA 256B may communicate with the AP 254A using a
third sub-channel and the STA 256H can communicate with the AP 254C
using the third sub-channel. Thus, the STA 256B can communicate at
the same time (and on at least some overlapping channels) as the
STA 256H. Because the STAs 256B and 256H are inner-cell devices,
they are unlikely to interfere with each other. In various
embodiments, the STAs 256B and 256H can also communicate on
different overlapping or non-overlapping sub-channels.
In some embodiments, one or more devices in each BSA can coordinate
frequency use and re-use so as to reduce or minimize the chances of
interference. For example, one or more devices in the first BSA
252A can transmit an instruction to one or more devices in the
first and/or second BSAs 252A and/or 252C, identifying sub-channels
for use by cell-edge devices in one or both BSAs 252A and 252C. For
example, the AP 254A can instruct the STA 256A to use a specific
sub-channel, and can subsequently instruct the STA 256A to use
another sub-channel. Likewise, the AP 254A can instruct the STA
256G to use a specific sub-channel, and can subsequently instruct
the STA 256G to use another sub-channel.
In another embodiment, cell-edge devices in the first BSA 252A can
simply start using a first sub-channel (or set of sub-channels).
For example, the cell-edge devices in the first BSA 252A can choose
a first sub-channel based on one or more RF characteristics such as
the sub-channel or set of sub-channels with the least interference.
The cell-edge devices in the second BSA 252C can observe the use of
the first sub-channel and can choose a second sub-channel (or set
of sub-channels). For example, new interference on the first
sub-channel may cause the cell-edge devices in the second BSA 252C
to choose the second sub-channel.
In some embodiments, frequency use and re-use can be uncoordinated.
For example, the cell-edge devices can be configured to hop between
sub-channels on a scheduled, random, or pseudo-random basis. Thus,
the STA 256A can use a specific sub-channel for a first period of
time, and can subsequently use another sub-channel. Likewise, the
STA 256G can use a specific sub-channel for a first period of time,
and can subsequently use another sub-channel. In some
circumstances, the STAs 256A and 256G might hop to the same
sub-channel by chance. However, they are also likely to
occasionally transmit on different channels.
FIG. 3 shows frequency multiplexing techniques that can be employed
within the wireless communication systems 100 of FIG. 1 and 250 of
FIG. 2B. As illustrated in FIG. 3, an AP 304A, 304B, 304C, and 304D
can be present within a wireless communication system 300. Each of
the APs 304A, 304B, 304C, and 304D can be associated with a
different BSA and include the high-efficiency wireless component
described herein.
As an example, an available bandwidth of the communication medium
can be set by a licensing body, a standards body, or preset or
detected by a device. For example, in an 802.11 standard, an
available bandwidth can be 80 MHz. Under a legacy 802.11 protocol,
each of the APs 304A, 304B, 304C, and 304D and the STAs associated
with each respective AP attempt to communicate using the entire
bandwidth, which can reduce throughput. In some instances, each
respective AP may reserve the entire bandwidth while actually
communicating only on a subset of available bandwidth. For example,
a legacy channel can have a 20 MHz bandwidth. However, under the
high-efficiency 802.11 protocol using frequency domain
multiplexing, the bandwidth can be divided into a plurality of
sub-channels. In the illustrated embodiment of FIG. 3, for example,
the 80 MHz available bandwidth is divided into four 20 MHz segments
308, 310, 312, and 314 (for example, channels). The AP 304A can be
associated with segment 308, the AP 304B can be associated with
segment 310, the AP 304C can be associated with segment 312, and
the AP 304D can be associated with segment 314. In various
embodiments, other size sub-channels can be used. For example,
sub-channels can be between about 1 MHz and 40 MHZ, between about 2
MHz and 10 MHz, and more particularly about 5 MHz. As discussed
above, sub-channels can be contiguous or non-contiguous (for
example, interleaved).
In an embodiment, when the APs 304A-304D and the STAs that are in a
state or condition such that the STAs can communicate concurrently
with other devices (for example, STAs near the center of the BSA)
are communicating with each other, then each AP 304A-304D and each
of these STAs may communicate using a portion of or the entire 80
MHz medium. However, when the APs 304A-304D and the STAs that are
in a state or condition such that the STAs cannot communicate
concurrently with other devices (for example, STAs near the edge of
the BSA) are communicating with each other, then AP 304A and its
STAs communicate using 20 MHz segment 308, AP 304B and its STAs
communicate using 20 MHz segment 310, AP 304C and its STAs
communicate using 20 MHz segment 312, and AP 304D and its STAs
communicate using 20 MHz segment 314. Because the segments 308,
310, 312, and 314 are different portions of the communication
medium, a first transmission using a first segment would not
interference with a second transmission using a second segment.
Thus, APs and/or STAs, even those that are in a state or condition
such that they cannot communicate concurrently with other devices,
that include the high-efficiency wireless component, can
communicate concurrently with other APs and STAs without
interference. Accordingly, the throughput of the wireless
communication system 300 can be increased. In the case of apartment
buildings or densely-populated public spaces, APs and/or STAs that
use the high-efficiency wireless component may experience reduced
latency and increased network throughput even as the number of
active wireless devices increases, thereby improving user
experience.
FIG. 4 shows an exemplary functional block diagram of a wireless
device 402 that can be employed within the wireless communication
systems 100, 250, and/or 300 of FIGS. 1, 2B, and 3. The wireless
device 402 is an example of a device that can be configured to
implement the various methods described herein. For example, the
wireless device 402 may comprise the AP 104, one of the STAs 106,
one of the APs 254, one of the STAs 256, and/or one of the APs
304.
The wireless device 402 may include a processor 404 which controls
operation of the wireless device 402. The processor 404 may also be
referred to as a central processing unit (CPU). Memory 406, which
may include both read-only memory (ROM) and random access memory
(RAM), may provide instructions and data to the processor 404. A
portion of the memory 406 may also include non-volatile random
access memory (NVRAM). The processor 404 typically performs logical
and arithmetic operations based on program instructions stored
within the memory 406. The instructions in the memory 406 can be
executable to implement the methods described herein.
The processor 404 may comprise or be a component of a processing
system implemented with one or more processors. The one or more
processors can be implemented with any combination of
general-purpose microprocessors, microcontrollers, digital signal
processors (DSPs), field programmable gate array (FPGAs),
programmable logic devices (PLDs), controllers, state machines,
gated logic, discrete hardware components, dedicated hardware
finite state machines, or any other suitable entities that can
perform calculations or other manipulations of information.
The processing system may also include machine-readable media for
storing software. Software shall be construed broadly to mean any
type of instructions, whether referred to as software, firmware,
middleware, microcode, hardware description language, or otherwise.
Instructions may include code (for example, in source code format,
binary code format, executable code format, or any other suitable
format of code). The instructions, when executed by the one or more
processors, cause the processing system to perform the various
functions described herein.
The wireless device 402 may also include a housing 408 that may
include a transmitter 410 and/or a receiver 412 to allow
transmission and reception of data between the wireless device 402
and a remote location. The transmitter 410 and receiver 412 can be
combined into a transceiver 414. An antenna 416 can be attached to
the housing 408 and electrically coupled to the transceiver 414.
The wireless device 402 may also include (not shown) multiple
transmitters, multiple receivers, multiple transceivers, and/or
multiple antennas.
The wireless device 402 may also include a signal detector 418 that
can be used in an effort to detect and quantify the level of
signals received by the transceiver 414. The signal detector 418
may detect such signals as total energy, energy per subcarrier per
symbol, power spectral density and other signals. The wireless
device 402 may also include a digital signal processor (DSP) 420
for use in processing signals. The DSP 420 can be configured to
generate a packet for transmission. In some aspects, the packet may
comprise a physical layer data unit (PPDU).
The wireless device 402 may further comprise a user interface 422
in some aspects. The user interface 422 may comprise a keypad, a
microphone, a speaker, and/or a display. The user interface 422 may
include any element or component that conveys information to a user
of the wireless device 402 and/or receives input from the user.
The wireless devices 402 may further comprise a high-efficiency
wireless component 424 in some aspects. The high-efficiency
wireless component 424 may include a classifier unit 428 and a
transmit control unit 430. As described herein, the high-efficiency
wireless component 424 may enable APs and/or STAs to use a modified
mechanism that minimizes the inefficiencies of the CSMA mechanism
(for example, enables concurrent communications over the medium in
situations in which interference would not occur).
The modified mechanism can be implemented by the classifier unit
428 and the transmit control unit 430. In an embodiment, the
classifier unit 428 determines which devices are in a state or
condition such that they can communicate concurrently with other
devices and which devices are in a state or condition such that
they cannot communicate concurrently with other devices. In an
embodiment, the transmit control unit 430 controls the behavior of
devices. For example, the transmit control unit 430 may allow
certain devices to transmit concurrently on the same medium and
allow other devices to transmit using a spatial multiplexing or
frequency domain multiplexing technique. The transmit control unit
430 may control the behavior of devices based on the determinations
made by the classifier unit 428.
The various components of the wireless device 402 can be coupled
together by a bus system 426. The bus system 426 may include a data
bus, for example, as well as a power bus, a control signal bus, and
a status signal bus in addition to the data bus. Those of skill in
the art will appreciate the components of the wireless device 402
can be coupled together or accept or provide inputs to each other
using some other mechanism.
Although a number of separate components are illustrated in FIG. 4,
those of skill in the art will recognize that one or more of the
components can be combined or commonly implemented. For example,
the processor 404 can be used to implement not only the
functionality described above with respect to the processor 404,
but also to implement the functionality described above with
respect to the signal detector 418 and/or the DSP 420. Further,
each of the components illustrated in FIG. 4 can be implemented
using a plurality of separate elements.
The wireless device 402 may comprise an AP 104, a STA 106, an AP
254, a STA 256, and/or an AP 304, and can be used to transmit
and/or receive communications. That is, either the AP 104, STA 106,
AP 254, STA 256, or AP 304 may serve as transmitter or receiver
devices. Certain aspects contemplate signal detector 418 being used
by software running on memory 406 and processor 404 to detect the
presence of a transmitter or receiver.
FIG. 5A shows the wireless communication system 500 in which
aspects of the present disclosure can be employed. As illustrated
in FIG. 5A, the wireless communication system 500 includes a BSA
502. The BSA 502 may include the AP 504 and STAs 506A-506E. In an
embodiment, the AP 504 and the STAs 506A-506D each include the
high-efficiency wireless component discussed above. However, the
STA 506E does not include the high-efficiency wireless component.
Thus, STAs 506A-506D are referred to as high-efficiency STAs,
whereas STA 506E is referred to as a legacy STA (for example,
because it is compatible with regular IEEE 802.11 protocols, such
as IEEE 802.11n, IEEE 802.11ac, etc.).
In some embodiments, the legacy STA 506E would reserve an entire
available bandwidth (for example, 80 MHz) while transmitting to a
legacy AP (which does not include the high-efficiency wireless
component) via a legacy channel (for example, 20 MHz). In an
embodiment, the high-efficiency AP 504 can be configured to receive
data on multiple sub-channels simultaneously. For example, the STA
506A can transmit to the AP 504 via uplink (UL) communication 510,
the STA 506B can transmit to the AP 504 via uplink (UL)
communication 512, and the STA 506C can transmit to the AP 504 via
uplink (UL) communication 514 at the same time as the STA 506E
transmits to the AP 504 via uplink (UL) communication 518. In the
illustrated embodiment, the UL communication 518 can be a legacy
channel communication, and the UL communications 510, 512, and 514
can be high-efficiency channel communications occupying unused
available sub-channels. In an embodiment, the STA 506D can also
transmit to the AP 504 via UL communication 516. As illustrated in
FIG. 5A, STAs 506A-506C can be located closer to the AP 504 than
STAs 506D-506E. The UL communications 510, 512, 514, 516, and 518
can be made by the AP 504 according to the uplink frequency domain
multiplexing (UL FDM) protocol described herein.
An UL FDM protocol may include three data exchange stages: (1) data
transmission; (2) protection; and (3) acknowledgment. The
protection stage may precede the data transmission stage and the
acknowledgment stage may follow the data transmission stage. In the
protection stage, techniques can be employed to prevent
interference. In the data transmission stage, data one or more STAs
may transmit data to the AP. In the acknowledgment stage, the STAs
may confirm that the AP received the appropriate data. Each of
these stages may occur concurrently on different channels according
to the frequency domain multiplexing principles discussed herein.
In addition, the UL FDM protocol may include rules related to the
timing of the start of transmissions by the STAs 306A-306E (FIG.
3).
Data Transmission Stage
During the UL data transmission stage, data is transmitted
simultaneously by multiple STAs on different channels. The STAs can
transmit on any channel discussed herein, particularly those within
the available bandwidth. In an embodiment, several data
transmission options are available during the data transmission
stage. In particular, several options are available for allocating
STAs on different channels such that the STAs can communicate
concurrently. These options may also allow for both legacy STAs and
high-efficiency STAs to communicate concurrently. Thus, the
techniques described herein to improve network throughput and
reduce latency can be implemented in devices that are compatible
with high-efficiency STAs and that are backwards compatible with
existing legacy STAs.
For example, an existing PHY layer of the regular IEEE 802.11
protocol (for example, the 802.11n, 802.11ac, etc.) can be coupled
with a new media access control (MAC) mechanism to allocate STAs on
different channels. As another example, a new PHY layer preamble
can be created for the high-efficiency 802.11 protocol and be used
by STAs on different channels. As another example, the existing PHY
layer of the regular IEEE 802.11 protocol and the new PHY layer
preamble can be used by STAs to transmit STAs on different channels
simultaneously or essentially simultaneously.
FIGS. 5B-5C show a timing diagram in which aspects of the present
disclosure can be employed. In particular, FIGS. 5B-5C show a
timing diagram that can be used in accordance with the existing PHY
layer of the regular IEEE 802.11 protocol and the new MAC
mechanism. As illustrated in FIGS. 5B-5C, four channels are
present: channel 520, channel 522, channel 524, and channel 526. As
discussed above, the term channel used herein can refer to any of a
contiguous portion of spectrum or a set of non-adjacent intervals
of spectrum, in which case the term bandwidth for the channel can
refer to the sum of the bandwidth of each interval. As used herein,
channel 526 is referred to as a primary channel (for example, a
default channel used by STAs operating on the regular IEEE 802.11
protocol) and channels 520, 522, and 524 are referred to as
secondary channels. In some embodiments, legacy STAs can only
transmit on secondary channels in combination with transmission on
the primary channel. In contrast, in various embodiments, HEW STAs
can transmit packets on the primary channel, on the primary channel
in combination with secondary channels, or on secondary channels
without including the primary channel. The channels 520, 522, 524,
and 526 can be contiguous (for example, each channel 520, 522, 524,
and 526 covers consecutive 20 MHz frequency ranges, such as from
1000 MHz to 1080 MHz) or non-contiguous (for example, there are
gaps in frequency between one or more of the channels 520, 522,
524, and/or 526).
In one embodiment all transmissions come from HEW STAs. In another
embodiment, one transmission comes from a legacy STA, and one or
more other transmissions come from one or more HEW STAs. In various
embodiments, the transmission bandwidth of each STA can be same or
can be different. In various embodiments, exemplary bandwidths used
by each STA can include one or more of 2.5 MHz, 5 MHz, 7.5 MHz, 10
MHz, 15 MHz, 20 MHz, 30 MHz, 40 MHz, 60 MHz, and 80 MHz. In some
embodiments, transmissions from all the STAs can be allocated such
that no transmissions are on adjacent channels.
In an embodiment, the primary channel (alone or in combination with
additional secondary channels, for example in legacy 11n/11ac
operation) is used for communications from legacy STAs (for
example, STA 506E) to the AP 504. Secondary channels are also used
for communications from high-efficiency STAs (for example, STAs
506A-506D) to the AP 504.
In various embodiments, duration of the transmission from multiple
STAs can be same or different. Different amounts of data and
different data rate used for the transmission can result in a
different time for the transmission of each data. In certain cases,
it is advantageous that all the transmissions end at the same time,
irrespective of the different minimum times that would be used by
each STA to send the data. In such cases where all the
transmissions end at the same time, each STA can include one or
more additional padding bytes to the frame, so that the frame
length matches a target frame length. The target duration can be
indicated in a frame received immediately before the transmission
(for example, the reference signals CTX described below with
respect to FIGS. 6A-6C), and/or can be previously negotiated or
indicated by the AP. In various embodiments, the padding operation
can be performed by adding one or more aggregated media access
control protocol data unit (A-MPDU) sub-frames and/or padding
bytes, for example as defined in the IEEE 802.11 ac standard.
In an embodiment, the AP 504 transmits, and the STAs 506A-506E
receive, a MAC message that associates the STAs 506A-506E with
channels, thereby indicating which channel the AP 504 plans to use
to communicate or receive a communication with a respective STA
506A-506E. In some embodiments, the AP 504 defaults to
communicating with the STA 506E on the primary channel since the
STA 506E is a legacy STA. Similarly, the STA 506E can default to
the primary channel for transmissions to the AP 504. Thus, the AP
504 may not transmit the MAC message to the STA 506E. Rather, the
AP 504 may transmit the MAC message only to the high-efficiency
STAs 506A-506D. In other embodiments, the AP 504 transmits the MAC
message to each STA 506A-506E. In various embodiments, the MAC
message can include one or more management frames sent from the AP
504 to the STAs 506A-506D, and can include an indication of the
allocated channel for each STA (either explicitly or implicitly
such as based on a categorization). In some embodiments, the MAC
message is referred to as a reference signal, described in greater
detail below with respect to FIG. 7A.
Channel Access
In various embodiments, it can be beneficial to synchronize the
start of transmission by the STAs 506A-506E. For example, it can be
easier to decode the transmissions when they start at the same
time. Because the STAs 506A-506E are disparate devices, however, it
can be challenging to coordinate a synchronized transmission time.
In various embodiments, transmission can be synchronized based on a
solicited or unsolicited reference signal from the AP 504. In other
embodiments, transmission can be synchronized based on a schedule
set by the AP 504 and/or STAs 506A-506E.
FIGS. 6A-6C show another timing diagram in which aspects of the
present disclosure can be employed. As described above, the primary
channel (for example, channel 526) and/or one or more of the
secondary channels (for example, channels 520, 522, and/or 524) can
be used for transmissions by legacy STAs and the primary channel
and/or secondary channels can be used for transmissions by
high-efficiency STAs. The channels 520,522,524, and/or 526 may or
may not be contiguous. In an embodiment, the AP 504 can transmit
one or more unsolicited reference signals CTX 601-604 to the STAs
506A-506E. The reference signals CTX 601-604 can indicate that STAs
with data to send should begin transmitting upon receipt (or at a
predetermined synchronization point after receipt). The
synchronization point can be at, for example, a short inter-frame
space (SIFS), a point coordination function (PCF) inter-frame space
(PIFS), or another predefined time after the end of reception of
the CTX frame. In an embodiment, the STAs 506A-506E receive the
reference signal CTX 601-604 can begin to transmit the
communications 510, 512, 514, and 518. The reference signals CTX
601-604 are described in greater detail herein with respect to FIG.
7A. In various embodiments, the synchronization point can be
referred to as a time of joint transmission.
As shown in FIG. 6A, the AP 504 can transmit the reference signal
CTX 601-602 on a plurality of sub-channels, or even all
sub-channels. In FIG. 6A, the STAs 506A-506E are only able to
receive on their assigned channel. Accordingly, the AP 504
transmits the reference signal CTX 601-604 on all channels. In some
embodiments, each CTXs can contain same information. In some
embodiments, various CTXs can contain different information on each
channel. In some embodiments, the STAs 506A-506E can receive the
reference signal on any channel. Accordingly, as shown in FIG. 6B,
the AP 504 may transmit a single reference signal CTX 602 on any
sub-channel that can be received by the STAs 506A-506E, for
example, on the primary channel.
The embodiment shown in FIG. 6C, the legacy STA 506E can only
receive the reference signal CTX 601 on the primary channel 526.
However, the HEW STAs 506A-506C are able to receive the reference
signal CTX 601 on any channel. Accordingly, the AP 504 transmits
the reference signal CTX 601 on the primary channel 526. In various
embodiments, other combinations of STA capability are possible.
In general, the AP 504 can be configured to transmit the reference
signals CTX 601-604 on a minimum number of sub-channels in order to
notify all target STAs. 506A-506E. In some embodiments, where more
than one sub-channel will suffice, the AP 504 may transmit a
reference signal CTX 601 on the sub-channel with the least
interference, or may transmit one or more redundant reference
signals CTX 601-604. The reference signals CTX 601-604 sent on
multiple sub-channels can be exactly same, or can be different per
sub-channel.
In an embodiment, a random back-off counter can be associated with
a CTX transmission channel (such as the primary channel 526 in FIG.
6C), as defined by the enhanced distributed channel access (EDCA)
procedure of IEEE 802.11. When the random back-off counter expires,
the AP 504 can begin preparing one or more reference signals CTX
601-604 for transmission to the STAs 506A-506E. If the intended CTX
transmission channel has been idle since a time period 610 before
the time that the random back-off counter expired, then the AP 504
may transmit the one or more reference signals CTX 601-604. Thus,
once the random back-off counter expires, at least one transmission
is made over the primary channel. In an embodiment, the time period
610 can be based on a PIFS time. The PIFS time can be chosen by the
AP 504 and/or STAs 506A-506E.
FIGS. 6D-6F show another timing diagram in which aspects of the
present disclosure can be employed. As described above, the primary
channel (for example, channel 526) and/or one or more of the
secondary channels (for example, channels 520, 522, and/or 524) can
be used for transmissions by legacy STAs and the secondary channels
can be used for transmissions by high-efficiency STAs. The channels
520, 522, 524, and/or 526 may or may not be contiguous. In an
embodiment, one or more STAs 506A-506E can request the reference
signals CTX 601-604 by transmitting a request-to-send (RTX) 620. In
various embodiments, an RTX can be compatible with legacy hardware.
For example, the RTX can include an RTS as defined in IEEE 802.11,
or can include another frame. In response, the AP 504 can transmit
one or more solicited reference signals CTX 601-604 to the STAs
506A-506E. The reference signals CTX 601-604 can indicate that STAs
with data to send should being transmitting upon receipt (or at a
predetermined synchronization point after receipt). In an
embodiment, the STAs 506A-506E receive the reference signal CTX
601-604 can begin to transmit the communications 510, 512, 514, and
518. As described in greater detail herein, CTX messages can
identify which STAs are allowed to transmit and on which
channels.
As shown in FIG. 6D, the AP 504 can transmit the reference signal
CTX 601-602 over a plurality of sub-channels, or even all
sub-channels. In FIG. 6A, the STAs 506A-506E are only able to
receive on their assigned channel. Accordingly, the AP 504
transmits the reference signal CTX 601-604 on all channels. In
other embodiments, the STAs 506A-506E can be able to receive the
reference signal on any channel. Accordingly, as shown in FIG. 6E,
the AP 504 may transmit a single reference signal CTX 602 on any
sub-channel that can be received by the STAs 506A-506E. In various
embodiments, the AP 504 may transmit a single reference signal CTX
602 on a different channel as the RTX 620. As shown in FIG. 6F, the
AP 504 may transmit a single reference signal CTX 602 on the same
channel as the RTX 620.
In general, the AP 504 can be configured to transmit the reference
signals CTX 601-604 on a minimum number of sub-channels in order to
notify all target STAs. 506A-506E. In some embodiments, where more
than one sub-channel will suffice, the AP 504 may transmit a
reference signal CTX 601 on the sub-channel with the least
interference, or may transmit one or more redundant reference
signals CTX 601-604.
In various embodiments, any STAs 506A-506E with data to send can
transmit the RTX 620, which can be compatible with legacy hardware
such as the STA 506E. In some embodiments, a STA transmits the RTX
620 on the same channel on which it will transmit data. In other
embodiments, the HEW STAs 506A-506E can transmit the RTX 620 on any
available channel, a channel with the least interference, a first
available channel according the EDCA, etc.
The STAs 506A-506E can transmit the RTX according to EDCA, as
discussed above with respect to the CTX 601-604. Particularly, a
random back-off counter can be associated with a RTX transmission
channel (such as the primary channel 526 in FIG. 6F), as defined by
the enhanced distributed channel access (EDCA) procedure of IEEE
802.11. When the random back-off counter expires, the STA 506E can
transmit an RTX frame 620 in a designated channel (for example, the
primary channel) for transmission to the AP 504. If additional
channels (for example, non-primary channels) RTX have been idle
since a time period 610 (see FIG. 6C) before the time that the
random back-off counter expired, then the STA 506E may transmit the
one or more RTX frames 620 on the primary and on the available
secondary channels. Upon reception of RTX, the AP 504 can respond
with a CTS or CTX frame in same set or subset of the channel where
the RTX is received, and can send a CTX in one or more additional
channels not within the channels where the RTX was received. In
particular, the channels where the CTX is sent can include the
channels where the medium was determined to be idle. In some
embodiments, the medium can be determined to be idle by checking
the channel for a PIFS time before the RTX reception or for a SIFS
time after the RTX reception. In an embodiment, the time period 610
can be based on a PIFS time. The PIFS time can be chosen by the AP
504 and/or STAs 506A-506E.
In one embodiment, the CTX can include information granting
transmission to the STA 506E on the channels where the RTX was sent
and can include information granting transmission to other STAs on
the channels where the RTX was not sent. In another embodiment, the
CTX can include information granting transmission for the STA 506
on a subset of the RTX channels and may grant transmission to other
STAs on the channels where the RTX was not sent.
The operation herein described, is advantageous at least because
RTX frames can be an RTX in a legacy format and can be sent by a
legacy STAs (such as the STA 506E), hence allowing a legacy STA to
initiate an UL transmit procedure. In some embodiments where the
RTX is sent by a legacy STA, the AP 504 can respond with a CTX
having a format compatible with the format of a legacy CTS, thus
enabling consistent operation at the STA. In various embodiments,
the AP 504 can detect whether an RTX was received from a legacy or
high efficiency STA by, for example, comparing a transmit address
with a stored lookup table. In other embodiments, the AP 504 can
detect whether an RTX was received from a legacy or high efficiency
STA by reading an explicit indication embedded in the legacy RTX
format.
In various embodiments, the RTX can include a control frame
including one or more of the following fields: a frame control, a
duration, a source address, a destination address, and an
information payload. The information payload can include one or
more of the following indications: a requested transmission time, a
size of a transmission queue, a quality-of-service (QoS) indication
for the requested transmission, and a requested transmission
bandwidth. The QoS indication can include, for example, a traffic
identifier (TID), a transport stream identifier (TSID), and/or any
other QoS Class). In various embodiments, the RTX control frame can
omit one or more fields discussed above and/or include one or more
fields not discussed above, including any of the fields discussed
herein. A person having ordinary skill in the art will appreciate
that the fields in the RTX control frame discussed above can be of
different suitable lengths, and can be in a different order. In
various embodiments, the RTX frame can include a data frame and can
additionally include a high throughput control (HTC) field with an
indication reverse decision grant (RDG)=1. In some embodiments,
such a frame according to IEEE 802.11 can signal that a portion
transmit opportunity indicated by the duration field and not used
by the current transmission can be used by the recipient AP. The
recipient AP can use the transmit opportunity to initiate an uplink
(UL) frequency division multiple access (FDMA) transmission in any
of the modes described herein.
In some embodiments, the AP 504 and/or the STAs 506A-506E can
determine a scheduled time at which the STAs 506A-506E should begin
transmitting. For example, scheduling mechanisms can be used to
define a time that the AP 504 should expect packets from the STAs
506A-506E. One scheduling mechanism can be based on a reference
time agreed between the AP and each individual STA via a management
exchange. In various embodiments, the reference time can be
periodic, intermittent, or randomly or pseudo randomly determined.
Selection of the reference time can be achieved with a protocol
such as a target wakeup time (TWT) timing, which is defined in the
IEEE 802.11 ah protocol. In some embodiments, the AP can define the
same reference time for multiple STAs by setting the TWT to same
value for multiple STAs. The TWT timing can be a time during which
a STA is scheduled to be awake. As another example, another
scheduling mechanism can be based on defining a reference time for
a group of STAs and an associated interval of time where access is
restricted to the group of STAs. For example, such scheduling can
be achieved with a restricted access window (RAW) timing, which is
defined in the IEEE 802.11ah protocol. The RAW timing can be an
interval of time during which access to a medium is restricted to a
group of STAs. In various embodiments, the interval of time can
further be slotted and each slot assigned to one or more STAs,
indicating that STAs can transmit UL data at the start of the slot
time.
At the reference time defined in any of above modes, STAs can be
ready to receive a CTX frame for initiating the transmission. In
some embodiments, STAs may start transmission without waiting for
the CTX. Thus, in various embodiments, STAs can be transmitting at
exactly the reference time, or it can perform a clear channel
assessment procedure on the intended transmission channel, starting
at the reference time. In various embodiments, the channel
assessment may require a PIFS time or DIFS time. If the target
channel is determined to be busy, the STA can refrain from
transmitting.
In another embodiment the STAs can be operating in HCCA mode,
during a Contention Free period. In thin case STAs are not allowed
to access the medium until a CF-Poll message is received (802.11);
the HCCA protocol can be modified such that the CF-Poll message
identifies more than one STAs for UL transmission at SIFS time
after the CF-Poll frame. The CF-Poll can be replaced with any of
the CTX frames described herein.
The AP 504 may further include in management messages used to set
up the scheduled time (for example, an RPS information element for
RAW, TWT setup messages for TWT, etc.) an indication of the channel
allocation for the benefit of the STAs. In another embodiment, the
allocation indicated by the AP 504 in such a message can be in
response to a message transmitted by a STA to the AP 504 requesting
the use of a specific channel or simply the allocation of a
channel. The message can be included in a management frame.
The transmissions from the STAs 506A-506E may start at the time
scheduled according to the TWT timing or the RAW timing. In an
embodiment, the random back-off counter, the PIFS timing, and/or
the AIFS timing can be used as described herein to determine
whether the channel has been idle for an appropriate amount of
time. A benefit of scheduling a transmission time based on the TWT
timing or the RAW timing can be that the AP 504 then knows when the
STAs 506A-506E will be awake. In another embodiment, the STAs
506A-506E may not use the random back-off counter, the PIFS timing,
and/or the AIFS timing. In still another embodiment, the STAs
506A-506E may not use the PIFS timing and/or the AIFS timing on
secondary channels.
In some embodiments, the AP 504 can transmit the reference signal
CTX 601-604 at the scheduled time. For example, the AP 504 can use
the same scheduling mechanism as the STAs 506A-506E (for example,
TWT timing or RAW timing) to determine when to transmit the
reference signal CTX 601-604. In an embodiment, the AP 504 can
transmit the reference signal CTX 601-604 after sensing the medium
as idle on the intended CTX channel. In various embodiments, the AP
504 can transmit the reference signal CTX as described above with
respect to the RTX 620. In various embodiments, the CTX message can
be sent once at the beginning of the RAW and be used for time synch
for all the slots in the RAW. In some embodiments, the CTX can be
sent at the start of each slot, providing synchronization and other
information per each transmission. Format of the Reference
Signal
In various embodiments, the reference signals CTX 601-604 can
include a clear-to-send frame, an extended clear-to-send frame,
and/or an aggregated MAC protocol data unit (MPDU) including a
clear-to-send frame and a new frame including an extended payload.
In some embodiments, reference signals can be referred to as MAC
messages. In various embodiments, one or more reference signals CTX
601-604 can include the same format (or compatible) as a legacy CTS
as defined in 802.11. In one embodiment, reference signals CTX
601-604 include a multicast MAC address, for example, in a receiver
address (RA) field of the CTS. In another embodiment, the reference
signals CTX 601-604 can have same format (compatible format) as a
CF-Poll frame as defined in 802.11 or a Synch frame as defined in
802.11ah. Poll frames can include a multicast receiver address.
In various embodiments, the reference signals CTX 601-604 can
include one or more of the following indications: a deferral time
for third party STAs, one or more identifiers of STAs that are
eligible to transmit via UL-FDMA at one certain (for example, a
short inter-frame space (SIFS), a point coordination function (PCF)
inter-frame space (PIFS), or longer) time after the reference
signal frame, indications of a power at which each of the STAs
506A-506E should transmit (for example, an indication of the
backoff with respect to a reference power), an indication, for each
STA, of the channel(s) and/or bandwidth the STAs 506A-506E should
use to transmit, channel assignments for one or more STAs, a time
synchronization indication, an ACK policy indication for one or
more STAs, an exact or maximum duration of the data transmission, a
number of spatial streams or number of space-time streams for each
STA, an indication of the length of all the information fields
included in the CTX, a timestamp or partial timestamp indicating a
time synchronization function (TSF) at the transmitter, etc. The
identifier of STAs that are eligible to transmit can include a list
of addresses (for example, MAC addressed, AIDs, partial or hashed
AIDs, etc.) and/or one or more group identifiers. The group
identifier can include, for example, a multicast MAC address
previously associated to a group of STAs and communicated to the
STAs, or a group identifier previously defined and communicated to
the STAs. The transmit power indicator can include, for example, an
absolute power indicator or an indication of a back-off from a STA
nominal transmit power, which the STAs 506A-506E can indicate. In
various embodiments, one or more of the aforementioned payload
elements can be negotiated or predetermined between each STA
506A-506E and the AP 504. The payload elements can be included in
an extended payload, or distributed in other fields.
FIG. 7A shows an example reference signal 700 that can be employed
within the wireless communication systems of FIGS. 1, 2B, and 3. In
the illustrated embodiment, the reference signal 700 includes a
frame control field 710, a duration field 720, a receive address
field 730, a frame check sequence (FCS) 740, and an extended
payload 750. As shown, the frame control field 710 is two bytes
long, the duration field 720 is two bytes long, the receive address
720 is six bytes long, the FCS 740 is four bytes long, and the
extended payload 750 is a variable length. In various embodiments,
the reference signal 700 can omit one or more fields shown in FIG.
7A and/or include one or more fields not shown in FIG. 7A,
including any of the fields discussed herein. A person having
ordinary skill in the art will appreciate that the fields in the
reference signal 700 can be of different suitable lengths, and can
be in a different order. In particular, the extended payload 750
can be omitted. In some embodiments, the reference signal 700 is a
clear-to-send frame.
In various embodiments, the extended payload 750 can include one or
more of the payload elements or indications discussed above.
Particularly, the extended payload can include a an identifier of
STAs that are eligible to transmit via UL-FDMA at a time after the
reference signal frame, an indication of a power at which the STAs
506A-506E should transmit, an indication of the channel(s) and/or
bandwidth the STAs 506A-506E should use to transmit, specific
channel assignments, and/or a synchronization indication. In
various embodiments, the time after the reference signal frame can
include a SIFS, a PIFS, or a time longer than PIFS. In various
embodiments, the time can be indicated by the AP 504 (FIG. 5A) in
the reference signal 700, or communicated by the AP 504 to STAs in
a previous message, or defined by the standard. The AP 504 can
define the time based on indications received from STAs
In an embodiment, the reference signal 700 can include an
indication that the reference signal 700 includes an extended CTS
frame including the extended payload 750. For example, the
reference signal 700 can set one or more bits normally reserved in
control frames to indicate the presence of the extended payload
750. Accordingly, a legacy STA 506E can be able to interpret at
least some fields of the CTS frame.
In some embodiments, the CTX frame can include one or more padding
bytes inserted after the information bytes. The purpose of the
padding byte can be to increase the length of the CTX, so as to
provide additional time for the processing of the CTX information
from the recipient STAs. The padding bytes can be identified as
following the information bytes, according to the length of the
information bytes indicated in one of the CTX fields.
In some embodiments, the reference signal 700 can omit the extended
payload 750 and/or include a control wrapper frame indicating the
presence of a high-throughput control (HTC) field. The HTC field
may provide four bytes that can be used to embed identifiers of
target STAs information. As another example, a special CTS message
may include additional information after the FCS field.
In some embodiments the CTX message can include a CTS message with
an HT Control field (for example, as defined in IEEE 802.11). The
presence of the HT Control (HTC) field in the CTS can be
identified, for example as defined in the IEEE 802.11 standard. The
HTC field can be overridden to carry one or more of the indications
listed above. The fact that the HTC is overridden to signal the
above information can be indicated by one or more of: the type of
PHY preamble used for the transmission, and one or more bits in the
HTC control field itself.
In some embodiments, the CTX can be a data frame and can include an
HTC field with reverse decision grant (RDG)=1, indicating that the
AP is allowing the recipient to use the remainder of the duration
time for a transmission. In particular, this may act as the trigger
indication for the UL FDMA transmissions. Moreover, the HTC field
can be overridden to carry the necessary information, as described
above.
In some embodiments, the CTX frame can be the same or similar to a
power save multi-poll (PSMP) frame (for example, as defined by the
802.11 standard), wherein the PSMP-UTT start offset within a STA
info field identifies the start time for the UL FDMA transmissions,
the PSMP UTT duration identifies the duration of the UL FDMA
transmission and the STA ID field may include an identifier of the
STAs allowed to transmit. Moreover the reserved bits can be used to
indicate a power backoff, a transmission bandwidth (BW), and/or a
channel allocation. Multiple STA info fields can be included in a
same PSMP frame, with a same value of start offset and duration,
hence indicating that multiple STAs can transmit in UL FDMA at the
indicated time.
FIG. 7B shows exemplary reference signal formats and fields that
can be employed within the wireless communication systems of FIGS.
1, 2B, and 3. In the illustrated embodiment, the reference signal
is the same or similar to a PSMP frame, as discussed above. In
various embodiments, the reference signal of FIG. 7B can omit one
or more fields shown in FIG. 7B and/or include one or more fields
not shown in FIG. 7B, including any of the fields discussed herein.
A person having ordinary skill in the art will appreciate that the
fields in the reference signal of FIG. 7B can be of different
suitable lengths, and can be in a different order.
As shown in FIG. 7B, a PSMP parameter set fixed field can include a
five-bit number of STAs field N_STA, a six-bit More PSMP field, and
a 10-bit PSMP Sequence Duration field. A PSMP STA Info fixed field,
when group addressed, can include a two-bit STA_INFO Type field
(set to "1"), an 11-bit PSMP-DTT Start Offset field, an 8-bit
PSMP-DTT Duration field, and a 43-bit PSMP Group Address ID. The
PSMP STA Info fixed field, when individually addressed, can include
a two-bit STA_INFO Type field (set to "2"), an 11-bit PSMP-DTT
Start Offset field, an 8-bit PSMP-DTT Duration field, a 16-bit
STA_ID field, an 11-bit PSMP-UTT Start Offset field, a 10-bit
PSMP-UTT Duration field, and six reserved bits. A PSMP frame Action
field can include a category field, an HT Action field, a PSMP
Parameter Set, and one or more PSMP STA Info fields repeated N_STA
times.
In various embodiments, a new value of the STA info type can be
used to indicate that the STA info field includes the start offset
field, the duration field, and a field identifying the multiple
STAs allowed to transmit (for example, as a group identifier, a
list of addresses or partial addresses, etc.). In some embodiments,
the group of destination STAs can be identified by the receive
address (RA) of the frame itself. In various embodiments, the
reference signal can otherwise include the rest of the PSMP frame
format. Advantageously, the use of the PSMP frame allows indicating
multiple UL and DL schedules for UL and DL transmissions.
FIG. 7C shows an example reference signal 760 that can be employed
within the wireless communication systems of FIGS. 1, 2B, and 3. In
the illustrated embodiment, the reference signal 760 includes the
frame control field 710, the duration field 720, the receive
address field 730, a transmit address field 762, a length field
764, a STA info field 766, one or more optional padding bits 768,
and the frame check sequence (FCS) 740. As shown, the frame control
field 710 is two bytes long, the duration field 720 is two bytes
long, the receive address 720 is six bytes long, the transmit
address field 762 is six bytes long, the length field 764 is one
byte long, the STA info field is a variable length N*X, the padding
bits 768 are a variable length M, and the FCS 740 is four bytes
long. In various embodiments, the reference signal 760 can omit one
or more fields shown in FIG. 7C and/or include one or more fields
not shown in FIG. 7C, including any of the fields discussed herein.
A person having ordinary skill in the art will appreciate that the
fields in the reference signal 760 can be of different suitable
lengths, and can be in a different order. In particular, the
receive address field 730, the length field 764, and/or the padding
bits 768 can be omitted. In some embodiments, the reference signal
760 is a clear-to-send frame.
In various embodiments, the RA 730 is present only in case it is
used for identifying the group of recipient STAs. The length field
764 may include either a length N in bytes of the information
portion 766, or a number X of STA info fields. The STA info field
766 can include one or more of the per-STA indications listed
above. In various embodiments, it can have the same length for each
STA. The padding bits 768 can include M byes of padding, to
increase the frame length.
In one embodiment, if the CTX message is sent over multiple
channels, any of the following is possible: it can be sent as a
single frame with a transmission BW spanning the total transmission
BW allocated for UL transmissions; it can be sent as a duplicate
across all the channels allocated for UL transmissions, i.e., the
content of each CTX is exactly the same across channels; and it can
be different per-channel, carrying different information for
different STAs receiving on different channels. In various
embodiments, CTSs sent on different channels with either different
BW or different information can have a different length, which may
be contrary to the purpose of providing a reference synchronization
time to all the STA for the UL transmission. Thus, in order for all
the CTSs to be of same length, each CTX can include a number of
padding bytes so that the length of all the CTXs is same.
In another embodiment, the CTX frame can be followed by an
additional "filler" frame sent by the same sender of the CTX, after
a SIFS time. The filler frame can serve to keep the medium busy and
provide additional time to the STAs for the processing and
interpretation of the CTX information and for the preparation of
the following UL transmission. In various embodiments, the filler
frame can be any of an null data packet (NDP), CTS, or other
control frame. The filler frame can also provide additional
protection for the upcoming transmissions.
In various embodiments, the need for, or inclusion of, padding
and/or a filler frame can be indicated by a STA to the AP with an
indication at association (for example, in an association request)
or through a management exchange. The STA can also indicate the
amount of time required for processing, which can determine the
amount of padding required.
When the transmission is initiated by the AP with a CTX,
advantageously the AP can schedule transmissions at a time where
multiple STAs are awake and have available data, hence maximizing
the efficiency. When using scheduled modes, the AP may also
indicate to the STAs that no transmission are allowed outside the
scheduled periods. This indication can be included in the beacon or
included in the setup phase (see "Setup," below) for each STA.
Transmission Eligibility
As discussed above, the AP 504 can indicate a list of STAs that are
eligible to transmit, for example in the reference signal 700 (FIG.
7A) or during transmission scheduling. STAs 506A-506E can indicate
that they have data to transmit in a QoS control field of any data
packet sent by the STAs 506A-506E to the AP 504. In an embodiment,
the STAs 506A-506E can transmit a QoS null data frame to the AP
504, which can include the QoS control field, to indicate that the
STA 506A-506E has buffered units for transmission. In some
embodiments, the STAs 506A-506E can transmit the QoS control field
in any data frame using regular contention procedures. The AP 504
can receive the QoS control field, determine which STAs 506A-506E
have data to transmit, and determine which STAs 506A-506E to
indicate for transmission eligibility.
In some embodiments, the STAs 506A-506E can indicate that they have
data to transmit by encoding an uplink data indication in a
power-save poll (PS-Poll) frame according to 802.11 ah. In some
embodiments, the STAs 506A-506E can indicate that they have data to
transmit by transmitting another frame via regular CSMA contention.
In some embodiments, the AP 504 can indicate a window during which
STAs 506A-506E should transmit indications that they have buffered
units. The window of time can be advertised in a Beacon and be
essentially similar to a RAW in some embodiments. The advertisement
can be achieved, for example, by using an RPS information element
as defined by the IEEE 802.11 ah standard, with the following
change: the type of the RAW is indicated to be for UL indication
only. The AP can also schedule a TWT with each individual STA for
allowing the STA to send an UL indication. Channel Allocation
FIG. 8 shows another timing diagram 850 in which aspects of the
present disclosure can be employed. As illustrated in FIG. 8, the
AP 504 transmits channel allocation messages 802, 804, 806, and 808
on each of the channels 520, 522, 524, and 526, respectively. The
channel allocation messages CHA 802, 804, 806, and 808 may provide
information to the STAs 506A-506E regarding which channel is
allocated to which STA. In some embodiments, the channel allocation
messages 802, 804, 806, and/or 808 can be the MAC message or
reference signal 800 (FIG. 8) described above.
In an embodiment, if the new PHY layer preamble 528 is available,
the PHY layer preamble 528 includes a group identification field
that corresponds to a channel allocation of the STAs of the
group.
In an embodiment, the channels can be pre-allocated, selected by
the STAs 506A-506E, and/or selected by the AP 506A-506E and
explicitly messaged via the channel allocation messages 802, 804,
806, and/or 808. The channel allocation messages 802, 804, 806,
and/or 808 can be sent at any time prior to the transmission by
each STA. In another embodiment, the AP 504 can include channel
allocation in the reference signals CTX 601-604 (FIGS. 6A-6F) or
MAC frames 802, 804, 806, and/or 808 sent immediately before the
data transmission 510, 512, 514, and/or 518. The channel allocation
can be indicated by one or more MAC addresses, AIDs, partial or
hashed AIDs, and corresponding channel identifiers.
In another embodiment, a group can be defined that includes
multiple STAs, each STA can be assigned a position in the group,
and the group can be identified by a group ID or by a multicast MAC
address. Thus, a channel allocated to a STA can be identified by
the group ID or multicast MAC address, and further by the position
of the STA in the group identified by the group ID. Messages for
setting up the group definitions can be sent at any time before the
UL-FDMA data transmissions 510, 512, 514, and/or 518 and can be
carried by management frames. Messages for indicating channel
allocation for a certain data transmission can be conveyed by
management or control frames sent before the data transmission 510,
512, 514, and/or 518 (for example, these frames may not be
transmitted based on SIFS or PIFS as described above), or can be
sent on a synchronization or MAC frame immediately preceding the
data transmission 510, 512, 514, and/or 518. In embodiments where
channel allocation is included in the reference messages CTX
601-604 or a CF-Poll frame, the receiver address can include a
multicast MAC address corresponding to a group and hence
identifying the channel for the STA.
In embodiments where the channels are pre-allocated, and when the
number of STAs is above a threshold and traffic requests from the
STAs are similar, then a random static allocation can be used (for
example, each STA is allocated to a channel, semi-statically). The
AP 504 may indicate to the STAs 506A-506E which station is
allocated to which channel (for example, via the channel allocation
messages 802, 804, 806, and/or 808). If the channels are selected
by the STAs 506A-506E, STAs 506A-506E may select and wait on a
channel preferred by the respective STA 506A-506E. The STAs
506A-506E may explicitly or implicitly (for example, via any
transmission) notify the AP 504 of their presence on the respective
channel.
In embodiments where the allocation is explicitly messaged, the
channel allocation messages 802, 804, 806, and/or 808 can be sent
on each of the channels or just a primary channel. Where the STAs
506A-506E implicitly notify the AP 504 of their presence, the AP
504 may know of a STA 506A-506E location based on reception of any
data, control, and/or management frame transmitted by the STA
506A-506E for regular operation. In other words, the data, control,
and/or management frame may not necessarily be designed for channel
indication. In embodiments where the STAs 506A-506E are able to
receive frames on multiple channels, the reception of a reference
signal addressed to a STA on an certain channel can implicitly
indicate that the certain channel is allocated to the addressed
STA. Particularly, the AP 504 can transmit multiple reference
frames CTX on multiple channels, each addressed to a different STA,
thereby defining the channel allocation.
Protection Stage
In various embodiments, as discussed above with respect to FIGS.
6D-6F request to send (RTX) and CTX messages are used by the AP 504
and the STAs 506A-506E to ensure that a given channel is free. The
duration field in RTX and CTS can indicate a duration that covers
the immediately following transmission, plus the required
acknowledgments.
Acknowledgment Stage
In an embodiment, restrictions can be placed on the duration of a
packet. In some embodiments, transmissions by the STAs 506A-506E
have different lengths. In other embodiments, transmissions by the
STAs 506A-506E have the same length.
Following the UL communications 510, 512, 514, and/or 518, the AP
504 may respond with a block acknowledgment (BA) acknowledging that
the DL communication was received. The AP 504 may respond with the
BA on its own volition or can be prompted to by the STAs 506A-506E
(for example, via a block acknowledgment request (BAR)). If the
STAs 506A-506E are all able to receive on any channel, or are all
able to receive on at least a same common channel (such as the
primary channel), the AP 504 may broadcast a single block
acknowledgment (BBA). The BBA frame carries block acknowledgment
indications for multiple STAs, possibly all the STAs that sent data
in UL. Additional information regarding BBA frames can be found in
U.S. Provisional Application No. 61/267,734, filed Dec. 8, 2009,
which is hereby incorporated by reference, and in an application
entitled "METHOD AND APPARATUS FOR MULTICAST BLOCK
ACKNOWLEDGEMENT," attached hereto.
In an embodiment, the BBA can be sent on the primary channel. In
various embodiments, APs 504 and/or STAs 506A-506E can transmit
BAs, BARs, and/or BBAs in a legacy or high-efficiency physical
protocol data unit (PPDU) format. In some embodiments where the APs
504 and/or STAs 506A-506E transmit BAs, BARs, and/or BBAs in high
efficiency PPDU format, the bandwidth can be smaller than 20 MHz.
Moreover different BAs, BARs, and/or BBAs can have different
durations, which can depend on a bandwidth used for transmission.
Timing diagrams included herein, and the various messages they
show, are not to scale.
FIGS. 9A-9C show additional timing diagrams in which aspects of the
present disclosure can be employed. In particular, FIGS. 9A-9C
illustrate the use of BAs, BARs, and BBAs as described herein. In
an embodiment, transmissions 51, 512, 514, and 518 do not end at
the same time, the AP 504 responds immediately with a BA after the
UL communication is complete. The AP 504 then responds to the
remaining transmissions with a BA after receiving a BAR. The STAs
506A-506E may transmit the BAR on the channel that the UL
communication was transmitted on, the primary channel, the
high-efficiency primary channel (for example, a primary channel
defined for use by the high-efficiency devices), and/or any other
channel.
For example, as illustrated in FIG. 9A, the AP 504 may respond with
a BA 904A after the UL communication 514 is complete. After the BA
904A has been received by the STA 506C, the STA 506C may transmit a
BAR 902B to the AP 504 on the channel 522, which is the channel
that the DL communication 512 was received by the STA 506B. Once
the AP 504 receives the BAR 902B, the AP 504 may respond with a BA
904B. The BAR and BA cycle then continues for the remaining STAs
(for example, STA 506A and STA 506E). The AP 504 can instruct the
STAs 506A-506E to set the acknowledgment policy of the data
transmitted by the STAs 506A-506E such that no more than one STA
506A-506E requests an immediate BA. In some embodiments, all the BA
policies can be set to BA (no immediate response required), but the
AP can nevertheless select one or more STAs and send an immediate
BA to them. The AP 504, after receiving an immediate acknowledgment
request or BAR, may transmit the acknowledgment or BA on the same
channel where data was received and/or on the primary channel. An
additional BAR can be sent by the STAs 506A-506E on the primary
channel and/or on one or more of the secondary channels, such as
the same channel where data was transmitted. In this case, the AP
504 may transmit the acknowledgment or BA on the same channel where
the BAR was received and/or on the primary channel.
In an embodiment, if the communications 510, 512, 514, and 518 end
at or near the same time and/or where STAs 506A-506E can only
receive on limited sub-channels, the AP 504 can respond with a BA
on each sub-channel after the UL communications are complete (for
example, end of transmission is a trigger for the AP 504 to send
the BAs). The BAs can be transmitted on the same channel as the
channel where the UL communication was received. For example, as
illustrated in FIG. 9B, the AP 504 response with a BA 904A-904D
immediately after the UL communications 510, 512, 514, and 518 are
complete. The BAs 904A-904D can be transmitted concurrently.
In embodiments where all STAs 506A-506E are able to decode a packet
on any channel, or the primary channel 526, the AP 504 can
broadcast a BBA after the UL communications 510, 512, 514, and 518
are complete. For example, as illustrated in FIG. 9C, the AP 504
transmits the BBA 904E on the primary channel 526 in response to
the termination of the UL communications 510, 512, 514, and 518 are
complete. Because all STAs 506A-506E can decode the BBA 904E, only
one is transmitted. Where one of the STAs 506A-506E is a legacy
STA, the AP 504 can instruct the high efficiency STAs to have a
transmission that is shorter than a transmission of the legacy STA.
The duration of transmission from the legacy STA can be inferred
from a duration field set in an RTX frame. Moreover the AP 504 can
instruct high-efficiency STAs to use a no-ACK policy.
Use Cases
In an embodiment, the UL FDM protocol described herein with respect
to FIGS. 5A-9C is implemented in several applications. For example,
a BSA may include legacy STAs and high-efficiency STAs. The UL FDM
protocol may use otherwise unused bandwidth in the communication
medium by assigning some of the STAs to a portion of the otherwise
unused bandwidth. This may allow the legacy STAs and/or the
high-efficiency STAs to communicate concurrently. This can be
beneficial if the BSS range of the wireless network is restricted
to high rate users.
As another example, frequency diversity can be achieved if the PHY
layer uses a tone interleaved approach. With frequency diversity, a
frequency hopping system is created that requires minimal
interference coordination. Tones can be divided into two or more
subsets. A first STA may transmit and/or receive data via tones in
the first subset and a second STA may transmit and/or receive data
via tones in the second subset. As long as the first subset and the
second subset do not overlap, interference can be avoided.
Setup
In various embodiments, the UL FDMA transmission can indicate
specific capabilities (for example, requested or required) to the
STA. STAs that do not have the indicated capabilities may not use
the UL FDMA transmission. Hence, the UL FDMA transmission may not
be used by all the STAs.
In some embodiments, the AP can determine which STAs are
potentially participating in the UL FDMA transmission. Each STA can
indicate its capability by setting one or more bits in a
Probe/Association request. In some embodiments, STAs can indicate
the willingness to participate in UL FDMA transmission by sending a
request to the AP through a management frame.
In various embodiments, the request can be carried in an additional
information field during the setup of a traffic specification
(TSPEC), for example, as defined by the IEEE 802.11 specification.
In various embodiments, the request can also be carried during
setup of an add BA (ADDBA) procedure. In various embodiments, the
request can be carried though a new management agreement, wherein
the STA sends a management frame to AP indicating the request and
additional relevant parameters for the operation, such as transmit
power capability, traffic pattern, QoS for which the procedure is
requested, time to process the CTX, etc.
In some embodiments, the STA advertising a capability may not
request the initiation of the use of UL FDMA. Instead, the AP may
request the STA the parameters required for the UL FDMA operation.
In some embodiments, the STA can be forced to accept the request.
In some embodiments, the STA may reject the request. In various
embodiments, the AP can also advertise its capability to receive UL
FDMA transmissions. Such advertisement can be indicated by one or
more bits in probe response, association response and/or
beacons.
Operation
In various embodiments, all options discussed herein can be
combined in an efficient way of using UL-FDMA. In particular, as
described above, the AP can define dedicated intervals of time for
DL/UL transmissions and for collecting requests from the STAs. In
one embodiment, the AP can schedule the operations such that the
following sequence of operations is achieved, wherein parentheses
indicate optionality, brackets indicate that the enclosed sequence
can be repeated multiple times within a beacon interval, and
operations are separated by semicolons: Beacon; [(restricted access
interval for PS-Polls or UL requests); restricted access interval
for DL transmission; restricted access interval for UL
transmissions]. In one embodiment, the AP can schedule the
operations such that the following sequence of operations is
achieved, wherein parentheses indicate optionality, brackets
indicate that the enclosed sequence can be repeated multiple times
within a beacon interval, and operations are separated by
semicolons: Beacon; [(restricted access interval for PS-Polls);
restricted access interval for DL transmission; (restricted access
interval for UL request); restricted access interval for UL
transmissions]. In one embodiment, the AP can schedule the
operations as shown in FIG. 9D.
FIG. 9D shows an additional timing diagram 990 in which aspects of
the present disclosure can be employed. In various embodiments, the
AP can protect or hold the medium for the entire sequence by means
of setting the NAV for all non-scheduled STAs or maintaining no
more than SIFS or PIFS time of medium idle across the entire
sequence. As shown in FIG. 9D, during a HEW transmit opportunity
(TXOP) 992 includes restricted access intervals for DL transmission
994, SIFS time (or shorter period) 996, a HEW UL random access
interval 998, and a HEW UL dedicated channel access interval
999.
As shown in FIG. 9D, the AP can gain access to the medium through
regular contention or through a predefined schedule. The AP may
then protect a certain interval of time referred to as transmission
opportunity (TXOP) 992. The protection may be achieved by sending a
frame that can set the NAV or through a scheduling that prevents
certain undesired STAs to transmit during the TXOP 992. During the
TXOP 992, the AP can schedule separate intervals of time for UL
communication, DL communication, and for collecting requests from
STAs for an UL communication. Within the UL communication interval,
any of the modes described herein can be used for UL FDMA
transmissions. Within the time reserved for indication of UL
traffic, a STA may use any of the methods described herein (QoS
Null, PS-Poll with uplink indication, and Data with More Data field
set). Moreover the transmission of such indication may be scheduled
by AP or can occur though contention. The AP can retain control on
the medium by making sure that no time greater than SIFS or PIFS is
unused within the TXOP 992.
Flowcharts
FIG. 10 shows a flowchart 1000 for an exemplary method of wireless
communication that can be employed within the wireless
communication system 500 of FIG. 5. The method can be implemented
in whole or in part by the devices described herein, such as the
wireless device 402 shown in FIG. 4. Although the illustrated
method is described herein with reference to the wireless
communication system 100 discussed above with respect to FIG. 1,
the wireless communication systems 200, 250, 300, and 500 discussed
above with respect to FIGS. 2-3 and 5A, and the wireless device 402
discussed above with respect to FIG. 4, a person having ordinary
skill in the art will appreciate that the illustrated method can be
implemented by another device described herein, or any other
suitable device. Although the illustrated method is described
herein with reference to a particular order, in various
embodiments, blocks herein can be performed in a different order,
or omitted, and additional blocks can be added.
First, at block 1010, an access point determines a performance
characteristic for each wireless device in a set of wireless
devices associated with the access point. For example, the AP 504
can determine one or more performance characteristics for each STA
506A-506E in the BSA 502. In various embodiments, the performance
characteristic can include physical and/or RF characteristics such
as, for example, a signal-to-interference-plus-noise ratio (SINR),
an RF geometry, a received signal strength indicator (RSSI), a
modulation and coding scheme (MCS) value, an interference level, a
signal level, a transmission capability, etc.
Then, at block 1020, the access point categorizes each wireless
device in the set into at least a first and second subset of
wireless devices based on the performance characteristic. The first
set of wireless devices can have a higher performance
characteristic than the second set of wireless devices. For
example, the AP 504 can categorize each STA 506A-506E in the BSA
502 into the first and second subsets. In an embodiment, the first
subset of wireless devices can include inner-cell devices and the
second subset of wireless devices can include cell-edge devices.
For example, the AP 504 could categorize the STAs 506A-506C as
inner-cell devices because they are physically close and might have
strong signal strength. In contrast, the AP 504 could categorize
the STAs 506D-506E as cell-edge devices because they are farther
away and can might have a lower SINR.
In various embodiments, the first subset of wireless devices can
have a higher signal-to-interference-plus-noise-ratio (SINR), a
higher geometry rating, a higher received signal strength indicator
(RSSI) than the second subset of wireless devices, or a greater
transmission capability. In one embodiment, the first subset of
wireless devices can have a higher modulation and coding scheme
(MCS) value than the second subset of wireless devices. In one
embodiment, the first subset of wireless devices can have a lower
interference than the second subset of wireless devices.
In some embodiments, the access point can assign the second set of
wireless frequencies to the second subset of wireless devices. For
example, the AP 504 can assign the channel 526 to the STA 506E. The
AP 504 can assign channels in coordination with other devices,
based on observed interference, etc.
In some embodiments, the access point can receive an indication of
the second set of wireless frequencies from at least one device in
the second subset of wireless devices. For example, the STA 506E
can make its own channel assignment, for example, based on observed
interference. The STA 506E can transmit the channel assignment to
the AP 504.
In some embodiments, the access point can transmit an indication of
the second set of wireless frequencies to one or more devices not
associated with the access point. For example, with reference to
FIG. 2B, the AP 254A can make one or more channel assignments and
can indicate the channel assignments of associated cell-edge
devices to, for example, the AP 254C and/or the STA 256G. In some
embodiments, the access point can receive an indication of the
second set of wireless frequencies from one or more devices not
associated with the access point. For example, the STA 256G could
instead make one or more channel assignments and can notify the AP
254A and/or the STA 256A.
In some embodiments, at least one wireless device in the second
subset of wireless devices can include a legacy device incapable of
transmitting on the entire first subset of frequencies. Returning
to FIG. 5A, for example, the STA 506E can be a legacy device. In
some embodiments, the STA 506E can be incapable of transmitting on
the entire first subset of frequencies such as, for example, where
it must transmit on a primary channel.
In some embodiments, the access point can receive a ready-to-send
(RTX) frame from at least one device in the second subset of
wireless devices. For example, the STA 506E can generate the RTX
620 (FIG. 6F) and transmit it to the AP 604. In some embodiments,
the access point can transmit a reference signal to at least one
device in the second subset of wireless devices. For example, the
AP 504 can transmit the reference signal CTX 601, in some instances
in response to the RTX 620 by transmitting.
In various embodiments, the reference signal can include an
indication of a deferral time for third party devices. In an
embodiment, the reference signal can include an indication of
devices that are eligible to transmit at a particular time. In an
embodiment, the reference signal can include an assignment of
channels to one or more devices in the second subset of wireless
devices. For example, the extended payload 750 (FIG. 7A) can
include one or more channel assignments or transmit authorizations.
In some embodiments, the transmit authorizations can include a list
of addresses of devices eligible to transmit at a particular time
(for example, the next SIFS time). The transmit authorizations can
include a group identifier defined in advance, for example, by the
AP 504.
In an embodiment, the reference signal can include an indication of
a power level at which at least one device should transmit. For
example, the extended payload 750 can include an indication of a
back-off from the STA's 506E nominal transmit power, which the STA
506E can indicate to the AP 504.
In various embodiments, the reference signal can include an
indication of a transmission time of at least one device in the
second subset of wireless devices. In an embodiment, the reference
signal can include a clear-to-send frame (CTS). In an embodiment,
the reference signal can include a clear-to-send frame (CTS) and an
extended payload comprising one or more payload elements. In an
embodiment, the reference signal can include a clear-to-send frame
(CTS) comprising a high-throughput control (HTC) field indicating
one or more target devices. In an embodiment, the reference signal
can include an aggregated media access control protocol data unit
(A-MPDU) comprising a clear-to-send frame (CTS) and one or more
payload elements. For example, the reference signal can include the
reference signal 700, described above with respect to FIG. 7A.
Next, at block 1130, the access point receives communications from
the first subset of wireless devices on a first set of wireless
frequencies. For example, the AP 504 can receive communications 510
from the STA 506A. In some embodiments, the communications 510 can
utilize an entire available bandwidth (for example, channels 308,
310, 312, and 314 of FIG. 3). In some embodiments, the
communications 510 can utilize only a portion of available
bandwidth.
Thereafter, at block 1140, the access point receives communications
from the second subset of wireless devices on a second set of
wireless frequencies. The second set of wireless frequencies is a
subset of the first. For example, the first subset can include
channels 526, 524, and 522. The second subset can include channel
526. Accordingly, the AP 504 can receive the communication 518 from
the STA 506E on the channel 526.
In other embodiments, the first and second sets of wireless
frequencies can be mutually exclusive. For example, the first
subset can include channels 522 and 520, and the second subset can
include channels 526 and 524. Accordingly, the first set of
wireless devices can contend normally for a portion of the
available bandwidth while the second set of wireless devices can
use FDMA to access another portion of the available bandwidth.
In some embodiments, the access point can concurrently receive
communications from each device in the second subset of wireless
devices. For example, the AP 504 can concurrently receive the
communication 518 from the STA 506E on the channel 524, and can
receive the communication 516 from the STA 506D on the channel 524
(not shown). In some embodiment, the access point can schedule a
time at which to receive communications from the second subset of
wireless devices.
In one embodiment, the access point can schedule a time at which to
receive communications from the second subset of wireless devices
and transmit a reference signal to at least one device in the
second subset of wireless devices at the scheduled time. For
example, at the scheduled transmit time, the AP 504 can transmit
the reference signal 700 to synchronize the STAs 506A-506E. In one
embodiment, the access point can receive, from at least one device
in the second subset of wireless devices, an indication that the at
least one device can be ready to send data. For example, the AP 504
can receive the RTX 620 from the STA 506E (FIG. 6F).
In some embodiments, the access point can receive, from at least
one device in the second subset of wireless devices, a
quality-of-service (QoS) field indicating that the at least one
device can be ready to send data. For example, the STA 506E can
transmit a QoS field to the AP 504 to indicate that it has data to
transmit. In another embodiment, the access point can receive, from
at least one device in the second subset of wireless devices, a
power-save poll (PS-Poll) frame indicating that the at least one
device can be ready to send data. For example, the STA 506E can
transmit the PS-Poll frame to the AP 504 to indicate that it has
data to transmit.
In various embodiments, the first subset of wireless frequencies
can include a 20 or 40 or 80 MHz channel according to an Institute
of Electrical and Electronics Engineers (IEEE) 802.11 standard. In
various embodiments, the first and second subset of wireless
frequencies can be within an operating bandwidth of the access
point.
In various embodiments, the first and second communications start
at the same time indicated by the reference signal, within a margin
of transmission time error. For example, the margin of transmission
time error can be a threshold value within which the first and
second communications start at substantially the same time. In
various embodiments, the first and second communications start at
different times.
In various embodiments, the first and second communications end at
the same time indicated by the reference signal, within a margin of
transmission time error. For example, the margin of transmission
time error can be a threshold value within which the first and
second communications end at substantially the same time. In
various embodiments, the first and second communications end at
different times.
In various embodiments the reference can be sent by the access
point according to a sense multiple access (CSMA) mechanism. In
various embodiments the reference signal can be sent by the access
point at a time previously scheduled with at least the first device
via management signaling. In various embodiments, the reference
signal is sent at least on a primary channel. In various
embodiments, the reference signal is sent on a primary channel and
on all or a portion of secondary channels that are idle for a
sensing time before the transmission. In various embodiments, the
reference signal is sent on channels compatible with the first and
second devices.
In various embodiments, the at least the first device indicates to
the access point a channel use capability. In various embodiments,
the reference signal is sent on idle channels only. In various
embodiments, the reference signal is sent on a primary channel
only, with an indication that only idle channels are to be
used.
In an embodiment, the method shown in FIG. 10 can be implemented in
a wireless device that can include a determining circuit, a
categorizing circuit, and a receiving circuit. Those skilled in the
art will appreciate that a wireless device can have more components
than the simplified wireless device described herein. The wireless
device described herein includes only those components useful for
describing some prominent features of implementations within the
scope of the claims.
The determining circuit can be configured to determine the
performance characteristic. In some embodiments, the generating
circuit can be configured to perform at least block 1010 of FIG.
10. The determining circuit can include one or more of the
processor 404 (FIG. 4), the DSP 420, the signal detector 418 (FIG.
4), the receiver 412 (FIG. 4), and the memory 406 (FIG. 4). In some
implementations, means for determining can include the determining
circuit.
The categorizing circuit can be configured to categorize each
wireless device. In some embodiments, the categorizing circuit can
be configured to perform at least block 1020 of FIG. 10. The
categorizing circuit can include one or more of the processor 404
(FIG. 4), the DSP 420, and the memory 406 (FIG. 4). In some
implementations, means for categorizing can include the
categorizing circuit.
The receiving circuit can be configured to receive communications
from the first and second subsets of wireless devices. In some
embodiments, the receiving circuit can be configured to perform at
least blocks 1030 and/or 1040 of FIG. 10. The receiving circuit can
include one or more of the receiver 412 (FIG. 4), the antenna 416
(FIG. 4), and the transceiver 414 (FIG. 4). In some
implementations, means for receiving can include the receiving
circuit.
FIG. 11 shows a flowchart 1100 for another exemplary method of
wireless communication that can be employed within the wireless
communication system 500 of FIG. 5. The method can be implemented
in whole or in part by the devices described herein, such as the
wireless device 402 shown in FIG. 4. Although the illustrated
method can be described herein with reference to the wireless
communication system 110 discussed above with respect to FIG. 1,
the wireless communication systems 200, 250, 300, and 500 discussed
above with respect to FIGS. 2-3 and 5A, and the wireless device 402
discussed above with respect to FIG. 4, a person having ordinary
skill in the art will appreciate that the illustrated method can be
implemented by another device described herein, or any other
suitable device. Although the illustrated method can be described
herein with reference to a particular order, in various
embodiments, blocks herein can be performed in a different order,
or omitted, and additional blocks can be added.
First, at block 1110, a first wireless device receives a reference
signal from an associated access point. The reference signal
indicates of a time of joint transmission with at least a second
wireless device. For example, the STA 506E can receive the
reference signal CTX 601 (FIG. 6C) from the AP 504.
Then, at block 1120, the first wireless device transmits a first
communication to the access point based on the reference signal.
The communication utilizes a first subset of wireless frequencies
available for use, and is concurrent with a second communication
from the second wireless device. The second communication utilizes
a second subset of wireless frequencies mutually exclusive with the
first subset. For example, the STA 506E can transmit the
communication 518 on the primary channel 526. Meanwhile, the STA
506A can transmit the communication 510 on the channel 524. The
channel 524 includes a set of frequencies that is mutually
exclusive with the set of frequencies in the channel 526. In an
embodiment, the first wireless device can receive the reference
signal on the second subset of wireless frequencies. For example,
the STA 506E can receive the reference signal CTX 602 on the
channel 524 (FIG. 6B), even though the STA 506E does not transmit
on the secondary channel 524.
In an embodiment, the first wireless device can transmit a request
for the reference signal to the access point. For example, the STA
506E can transmit the RTX 620 (FIG. 6F) on the channel 526. In an
embodiment, the first wireless device can transmit a request for
the reference signal to the access point on the second subset of
wireless frequencies. For example, the STA 506E can transmit the
RTX 620 on the channel 524 (FIG. 6D) even though the STA 506E does
not transmit the communication 518 on the channel 524. In an
embodiment, the first wireless device can transmit a ready-to-send
(RTX) frame to the access point. For example, the STA 506E can
transmit the RTX 620.
In an embodiment, the first wireless device can receive an
indication of the first subset of wireless frequencies from the
access point. For example, the AP 504 can assign the STA 506E the
channel 526 for transmitting the communication 518. The AP 504 can
indicate the channel 526 in, for example, the reference signal 700
described above with respect to FIG. 7A. In an embodiment, the
first wireless device can receive an indication of the first set of
wireless frequencies from one or more devices not associated with
the access point. For example, with reference to FIG. 2B, the STA
256A can receive a channel assignment from the STA 256G and/or the
AP 254C.
In an embodiment, the first wireless device can detect an
interference level on one or more wireless frequencies and
determine the first subset of wireless frequencies based on the
interference level. For example, with reference to FIG. 6A, the STA
506E might detect relatively high interference levels on the
channels 524, 522, and 520, as compared to the channel 526.
Accordingly, the STA 506E might determine that it should transmit
the communication 518 on the channel 526.
In an embodiment, the first wireless device can determine the first
subset of wireless frequencies based on a tone interleaved channel
with frequency hopping. For example, the STA 506E might determine
to hop between the channel 524 and the channel 526. As another
example, the channel 526 can include a tone interleaved channel
with built-in frequency hopping. Accordingly, the STA 506E can stay
on the channel 526 as the particular frequencies in channel 526
change.
In an embodiment, the first wireless device can transmit an
indication of the first subset of wireless frequencies to the
access point. For example, after the STA 506E determines it will
transmit the communication 518 on the channel 526, it can transmit
the channel selection to the AP 504, for example in a QoS field
and/or a PS-Poll frame. In an embodiment, the first wireless device
can transmit an indication of the first set of wireless frequencies
to one or more devices not associated with the access point. For
example, with reference to FIG. 2B, after the STA 256A chooses a
channel, it can indicate the channel selection to the STA 256G
and/or the AP 254C.
In an embodiment, the reference signal can include an indication of
a deferral time for third party devices. In an embodiment, the
reference signal can include an indication of devices that are
eligible to transmit at a particular time. In an embodiment, the
reference signal can include an indication of a power level at
which at least one device should transmit.
In various embodiments, the reference signal can include an
indication of a deferral time for third party devices. In an
embodiment, the reference signal can include an indication of
devices that are eligible to transmit at a particular time. In an
embodiment, the reference signal can include an assignment of
channels to one or more devices in the second subset of wireless
devices. For example, the extended payload 750 (FIG. 7A) can
include one or more channel assignments or transmit authorizations.
In some embodiments, the transmit authorizations can include a list
of addresses of devices eligible to transmit at a particular time
(for example, the next SIFS time). The transmit authorizations can
include a group identifier defined in advance, for example, by the
AP 504.
In an embodiment, the reference signal can include an indication of
a power level at which at least one device should transmit. For
example, the extended payload 750 can include an indication of a
back-off from the STA's 506E nominal transmit power, which the STA
506E can indicate to the AP 504.
In various embodiments, the reference signal can include an
indication of a transmission time of at least one device in the
second subset of wireless devices. In an embodiment, the reference
signal can include a clear-to-send frame (CTS). In an embodiment,
the reference signal can include a clear-to-send frame (CTS) and an
extended payload comprising one or more payload elements. In an
embodiment, the reference signal can include a clear-to-send frame
(CTS) comprising a high-throughput control (HTC) field indicating
one or more target devices. In an embodiment, the reference signal
can include an aggregated media access control protocol data unit
(A-MPDU) comprising a clear-to-send frame (CTS) and one or more
payload elements. For example, the reference signal can include the
reference signal 700, described above with respect to FIG. 7A.
In an embodiment, the first wireless device can schedule a time at
which to transmit communications to the access point. In an
embodiment, the first wireless device can transmit to the access
point an indication that the first device can be ready to send
data. In an embodiment, the first wireless device can transmit to
the access point a quality-of-service (QoS) field indicating that
the first device can be ready to send data. In an embodiment, the
first wireless device can transmit to the access point a power-save
poll (PS-Poll) frame indicating that the first device can be ready
to send data. For example, the STA 506E can transmit the various
messages discussed herein to the AP 504.
In an embodiment, the method shown in FIG. 11 can be implemented in
a wireless device that can include a receiving circuit, and a
transmitting circuit. Those skilled in the art will appreciate that
a wireless device can have more components than the simplified
wireless device described herein. The wireless device described
herein includes only those components useful for describing some
prominent features of implementations within the scope of the
claims.
The receiving circuit can be configured to receive the reference
signal. In some embodiments, the receiving circuit can be
configured to perform at least block 1110 of FIG. 11. The receiving
circuit can include one or more of the receiver 412 (FIG. 4), the
antenna 416 (FIG. 4), and the transceiver 414 (FIG. 4). In some
implementations, means for receiving can include the receiving
circuit.
The transmitting circuit can be configured to transmit the first
communication. In some embodiments, the transmitting circuit can be
configured to perform at least block 1120 of FIG. 11. The
transmitting circuit can include one or more of the transmitter 410
(FIG. 4), the antenna 416 (FIG. 4), and the transceiver 414 (FIG.
4). In some implementations, means for transmitting can include the
transmitting circuit.
FIG. 12 shows a flowchart 1200 for an exemplary method of wireless
communication that can be employed within the wireless
communication system 500 of FIG. 5. The method can be implemented
in whole or in part by the devices described herein, such as the
wireless device 402 shown in FIG. 4. Although the illustrated
method is described herein with reference to the wireless
communication system 120 discussed above with respect to FIG. 1,
the wireless communication systems 200, 250, 300, and 500 discussed
above with respect to FIGS. 2-3 and 5A, and the wireless device 402
discussed above with respect to FIG. 4, a person having ordinary
skill in the art will appreciate that the illustrated method can be
implemented by another device described herein, or any other
suitable device. Although the illustrated method is described
herein with reference to a particular order, in various
embodiments, blocks herein can be performed in a different order,
or omitted, and additional blocks can be added.
First, at block 1210, the access point exchanges at least one
protection frame with at least one of a first and second wireless
device. In an embodiment, exchanging at least one protection frame
can include receiving a ready-to-send (RTX) frame from at least one
of the first and second device. In an embodiment, exchanging at
least one protection frame can include transmitting a reference
signal to the first and second device. For example, the AP 504 can
exchange the RTX 620 and/or the reference signal CTX 602 (FIG. 6D)
with the STAs 506A-506E.
In various embodiments, the reference signal can include an
indication of a deferral time for third party devices. In an
embodiment, the reference signal can include an indication of
devices that are eligible to transmit at a particular time. In an
embodiment, the reference signal can include an assignment of
channels to one or more devices in the second subset of wireless
devices. For example, the extended payload 750 (FIG. 7A) can
include one or more channel assignments or transmit authorizations.
In some embodiments, the transmit authorizations can include a list
of addresses of devices eligible to transmit at a particular time
(for example, the next SIFS time). The transmit authorizations can
include a group identifier defined in advance, for example, by the
AP 504.
In an embodiment, the reference signal can include an indication of
a power level at which at least one device should transmit. For
example, the extended payload 750 can include an indication of a
back-off from the STA's 506E nominal transmit power, which the STA
506E can indicate to the AP 504.
In various embodiments, the reference signal can include an
indication of a transmission time of at least one device in the
second subset of wireless devices. In an embodiment, the reference
signal can include a clear-to-send frame (CTS). In an embodiment,
the reference signal can include a clear-to-send frame (CTS) and an
extended payload comprising one or more payload elements. In an
embodiment, the reference signal can include a clear-to-send frame
(CTS) comprising a high-throughput control (HTC) field indicating
one or more target devices. In an embodiment, the reference signal
can include an aggregated media access control protocol data unit
(A-MPDU) comprising a clear-to-send frame (CTS) and one or more
payload elements. For example, the reference signal can include the
reference signal 700, described above with respect to FIG. 7A.
In an embodiment, the access point can assign the first and/or
second set of wireless frequencies to the first and/or second
device, respectively. For example, the AP 504 can assign the
channel 526 to the STA 506E. The AP 504 can assign channels in
coordination with other devices, based on observed interference,
etc. In an embodiment, the access point can receive an indication
of the first and/or second set of wireless frequencies from the
first and/or second device, respectively. For example, the STA 506E
can make its own channel assignment, for example, based on observed
interference. The STA 506E can transmit the channel assignment to
the AP 504.
In an embodiment, the first wireless device can include a legacy
device incapable simultaneously transmitting on the entire set of
wireless frequencies available for use by both the first and second
wireless device. Returning to FIG. 5A, for example, the STA 506E
can be a legacy device. In some embodiments, the STA 506E can be
incapable of transmitting on the entire first subset of frequencies
such as, for example, where it must transmit on a primary
channel.
Then, at block 1220, the access point receives a first
communication on a first set of wireless frequencies from the first
wireless device. For example, the AP 504 can receive the
communication 518 from the STA 506E on the primary channel 526.
Next, at block 1230, the access point receives a second
communication, at least partially concurrent with the first
communication, on a second set of wireless frequencies from the
second wireless device. The first set and the second set are
mutually exclusive subsets of a set of wireless frequencies
available for use by both the first and second wireless device. For
example, the AP 504 can receive the communication 510 from the STA
506A on the channel 524. The frequencies of the channels 526 and
526 are mutually exclusive.
Thereafter, at block 1240, the access point transmits at least one
acknowledgment of the first and second communication. For example,
the AP 504 can transmit the BA 904A (FIG. 9A). In an embodiment,
the access point transmits a single broadcast acknowledgment on
only the first subset of frequencies. For example, the AP 504 can
transmit only the BBA 904E (FIG. 9C) on the primary channel 526. In
an embodiment, the access point receives an acknowledgment request
and transmits the acknowledgment in response to the acknowledgment
request. For example, the AP 504 can receive a BAR 902B (FIG. 9A)
from the STA 506B on the channel 522, and can respond with the BA
904B on the channel 522.
In some embodiment, the access point can schedule a time at which
to receive communications from the second subset of wireless
devices. In one embodiment, the access point can schedule a time at
which to receive communications from the second subset of wireless
devices and transmit a reference signal to at least one device in
the second subset of wireless devices at the scheduled time. For
example, at the scheduled transmit time, the AP 504 can transmit
the reference signal 700 to synchronize the STAs 506A-506E. In one
embodiment, the access point can receive, from at least one device
in the second subset of wireless devices, an indication that the at
least one device can be ready to send data. For example, the AP 504
can receive the RTX 620 from the STA 506E (FIG. 6F).
In some embodiments, the access point can receive, from at least
one device in the second subset of wireless devices, a
quality-of-service (QoS) field indicating that the at least one
device can be ready to send data. For example, the STA 506E can
transmit a QoS field to the AP 504 to indicate that it has data to
transmit. In another embodiment, the access point can receive, from
at least one device in the second subset of wireless devices, a
power-save poll (PS-Poll) frame indicating that the at least one
device can be ready to send data. For example, the STA 506E can
transmit the PS-Poll frame to the AP 504 to indicate that it has
data to transmit.
In an embodiment, the method shown in FIG. 12 can be implemented in
a wireless device that can include an exchanging circuit, a
receiving circuit, and a transmitting circuit. Those skilled in the
art will appreciate that a wireless device can have more components
than the simplified wireless device described herein. The wireless
device described herein includes only those components useful for
describing some prominent features of implementations within the
scope of the claims.
The exchanging circuit can be configured to exchange the protection
frame. In some embodiments, the exchanging circuit can be
configured to perform at least block 1210 of FIG. 12. The
exchanging circuit can include one or more of the transmitter 410
(FIG. 4), the receiver 412 (FIG. 4), the antenna 416 (FIG. 4), and
the transceiver 414 (FIG. 4). In some implementations, means for
exchanging can include the exchanging circuit.
The receiving circuit can be configured to receive communications
from the first and second wireless devices. In some embodiments,
the receiving circuit can be configured to perform at least blocks
1220 and/or 1230 of FIG. 12. The receiving circuit can include one
or more of the receiver 412 (FIG. 4), the antenna 416 (FIG. 4), and
the transceiver 414 (FIG. 4). In some implementations, means for
receiving can include the receiving circuit.
The transmitting circuit can be configured to transmit the
acknowledgment. In some embodiments, the transmitting circuit can
be configured to perform at least block 1240 of FIG. 12. The
transmitting circuit can include one or more of the transmitter 410
(FIG. 4), the antenna 416 (FIG. 4), and the transceiver 414 (FIG.
4). In some implementations, means for transmitting can include the
transmitting circuit.
As used herein, the term "determining" encompasses a wide variety
of actions. For example, "determining" may include calculating,
computing, processing, deriving, investigating, looking up (for
example, looking up in a table, a database or another data
structure), ascertaining and the like. Also, "determining" may
include receiving (for example, receiving information), accessing
(for example, accessing data in a memory) and the like. Also,
"determining" may include resolving, selecting, choosing,
establishing and the like. Further, a "channel width" as used
herein may encompass or may also be referred to as a bandwidth in
certain aspects.
As used herein, a phrase referring to "at least one of" a list of
items refers to any combination of those items, including single
members. As an example, "at least one of: a, b, or c" is intended
to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
The various operations of methods described above can be performed
by any suitable means capable of performing the operations, such as
various hardware and/or software component(s), circuits, and/or
module(s). Generally, any operations illustrated in the Figures can
be performed by corresponding functional means capable of
performing the operations.
The various illustrative logical blocks, modules and circuits
described in connection with the present disclosure can be
implemented or performed with a general purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array signal (FPGA) or
other programmable logic device (PLD), discrete gate or transistor
logic, discrete hardware components or any combination thereof
designed to perform the functions described herein. A general
purpose processor can be a microprocessor, but in the alternative,
the processor can be any commercially available processor,
controller, microcontroller or state machine. A processor may also
be implemented as a combination of computing devices, for example,
a combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
In one or more aspects, the functions described can be implemented
in hardware, software, firmware, or any combination thereof. If
implemented in software, the functions can be stored on or
transmitted over as one or more instructions or code on a
computer-readable medium. Computer-readable media includes both
computer storage media and communication media including any medium
that facilitates transfer of a computer program from one place to
another. A storage media can be any available media that can be
accessed by a computer. By way of example, and not limitation, such
computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or
other optical disk storage, magnetic disk storage or other magnetic
storage devices, or any other medium that can be used to carry or
store desired program code in the form of instructions or data
structures and that can be accessed by a computer. Also, any
connection is properly termed a computer-readable medium. For
example, if the software is transmitted from a website, server, or
other remote source using a coaxial cable, fiber optic cable,
twisted pair, digital subscriber line (DSL), or wireless
technologies such as infrared, radio, and microwave, then the
coaxial cable, fiber optic cable, twisted pair, DSL, or wireless
technologies such as infrared, radio, and microwave are included in
the definition of medium. Disk and disc, as used herein, includes
compact disc (CD), laser disc, optical disc, digital versatile disc
(DVD), floppy disk, and Blu-ray.RTM. disc where disks usually
reproduce data magnetically, while discs reproduce data optically
with lasers. Thus, in some aspects, computer readable medium may
comprise non-transitory computer readable medium (for example,
tangible media). In addition, in some aspects computer readable
medium may comprise transitory computer readable medium (for
example, a signal). Combinations of the above should also be
included within the scope of computer-readable media.
Thus, certain aspects may comprise a computer program product for
performing the operations presented herein. For example, such a
computer program product may comprise a computer readable medium
having instructions stored (and/or encoded) thereon, the
instructions being executable by one or more processors to perform
the operations described herein. For certain aspects, the computer
program product may include packaging material.
The methods disclosed herein comprise one or more steps or actions
for achieving the described method. The method steps and/or actions
can be interchanged with one another without departing from the
scope of the claims. In other words, unless a specific order of
steps or actions is specified, the order and/or use of specific
steps and/or actions can be modified without departing from the
scope of the claims.
Software or instructions may also be transmitted over a
transmission medium. For example, if the software is transmitted
from a website, server, or other remote source using a coaxial
cable, fiber optic cable, twisted pair, digital subscriber line
(DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of transmission
medium.
Further, it should be appreciated that modules and/or other
appropriate means for performing the methods and techniques
described herein can be downloaded and/or otherwise obtained by a
user terminal and/or base station as applicable. For example, such
a device can be coupled to a server to facilitate the transfer of
means for performing the methods described herein. Alternatively,
various methods described herein can be provided via storage means
(for example, RAM, ROM, a physical storage medium such as a compact
disc (CD) or floppy disk, etc.), such that a user terminal and/or
base station can obtain the various methods upon coupling or
providing the storage means to the device. Moreover, any other
suitable technique for providing the methods and techniques
described herein to a device can be utilized.
It is to be understood that the claims are not limited to the
precise configuration and components illustrated above. Various
modifications, changes and variations can be made in the
arrangement, operation and details of the methods and apparatus
described above without departing from the scope of the claims.
While the foregoing is directed to aspects of the present
disclosure, other and further aspects of the disclosure can be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
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